/*
* zcache.c
*
* Copyright (c) 2010,2011, Dan Magenheimer, Oracle Corp.
* Copyright (c) 2010,2011, Nitin Gupta
*
* Zcache provides an in-kernel "host implementation" for transcendent memory
* and, thus indirectly, for cleancache and frontswap. Zcache includes two
* page-accessible memory [1] interfaces, both utilizing lzo1x compression:
* 1) "compression buddies" ("zbud") is used for ephemeral pages
* 2) xvmalloc is used for persistent pages.
* Xvmalloc (based on the TLSF allocator) has very low fragmentation
* so maximizes space efficiency, while zbud allows pairs (and potentially,
* in the future, more than a pair of) compressed pages to be closely linked
* so that reclaiming can be done via the kernel's physical-page-oriented
* "shrinker" interface.
*
* [1] For a definition of page-accessible memory (aka PAM), see:
* http://marc.info/?l=linux-mm&m=127811271605009
*/
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/highmem.h>
#include <linux/list.h>
#include <linux/lzo.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/atomic.h>
#include <linux/math64.h>
#include "tmem.h"
#include "../zram/xvmalloc.h" /* if built in drivers/staging */
#if (!defined(CONFIG_CLEANCACHE) && !defined(CONFIG_FRONTSWAP))
#error "zcache is useless without CONFIG_CLEANCACHE or CONFIG_FRONTSWAP"
#endif
#ifdef CONFIG_CLEANCACHE
#include <linux/cleancache.h>
#endif
#ifdef CONFIG_FRONTSWAP
#include <linux/frontswap.h>
#endif
#if 0
/* this is more aggressive but may cause other problems? */
#define ZCACHE_GFP_MASK (GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN)
#else
#define ZCACHE_GFP_MASK \
(__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC)
#endif
#define MAX_POOLS_PER_CLIENT 16
#define MAX_CLIENTS 16
#define LOCAL_CLIENT ((uint16_t)-1)
MODULE_LICENSE("GPL");
struct zcache_client {
struct tmem_pool *tmem_pools[MAX_POOLS_PER_CLIENT];
struct xv_pool *xvpool;
bool allocated;
atomic_t refcount;
};
static struct zcache_client zcache_host;
static struct zcache_client zcache_clients[MAX_CLIENTS];
static inline uint16_t get_client_id_from_client(struct zcache_client *cli)
{
BUG_ON(cli == NULL);
if (cli == &zcache_host)
return LOCAL_CLIENT;
return cli - &zcache_clients[0];
}
static inline bool is_local_client(struct zcache_client *cli)
{
return cli == &zcache_host;
}
/**********
* Compression buddies ("zbud") provides for packing two (or, possibly
* in the future, more) compressed ephemeral pages into a single "raw"
* (physical) page and tracking them with data structures so that
* the raw pages can be easily reclaimed.
*
* A zbud page ("zbpg") is an aligned page containing a list_head,
* a lock, and two "zbud headers". The remainder of the physical
* page is divided up into aligned 64-byte "chunks" which contain
* the compressed data for zero, one, or two zbuds. Each zbpg
* resides on: (1) an "unused list" if it has no zbuds; (2) a
* "buddied" list if it is fully populated with two zbuds; or
* (3) one of PAGE_SIZE/64 "unbuddied" lists indexed by how many chunks
* the one unbuddied zbud uses. The data inside a zbpg cannot be
* read or written unless the zbpg's lock is held.
*/
#define ZBH_SENTINEL 0x43214321
#define ZBPG_SENTINEL 0xdeadbeef
#define ZBUD_MAX_BUDS 2
struct zbud_hdr {
uint16_t client_id;
uint16_t pool_id;
struct tmem_oid oid;
uint32_t index;
uint16_t size; /* compressed size in bytes, zero means unused */
DECL_SENTINEL
};
struct zbud_page {
struct list_head bud_list;
spinlock_t lock;
struct zbud_hdr buddy[ZBUD_MAX_BUDS];
DECL_SENTINEL
/* followed by NUM_CHUNK aligned CHUNK_SIZE-byte chunks */
};
#define CHUNK_SHIFT 6
#define CHUNK_SIZE (1 << CHUNK_SHIFT)
#define CHUNK_MASK (~(CHUNK_SIZE-1))
#define NCHUNKS (((PAGE_SIZE - sizeof(struct zbud_page)) & \
CHUNK_MASK) >> CHUNK_SHIFT)
#define MAX_CHUNK (NCHUNKS-1)
static struct {
struct list_head list;
unsigned count;
} zbud_unbuddied[NCHUNKS];
/* list N contains pages with N chunks USED and NCHUNKS-N unused */
/* element 0 is never used but optimizing that isn't worth it */
static unsigned long zbud_cumul_chunk_counts[NCHUNKS];
struct list_head zbud_buddied_list;
static unsigned long zcache_zbud_buddied_count;
/* protects the buddied list and all unbuddied lists */
static DEFINE_SPINLOCK(zbud_budlists_spinlock);
static LIST_HEAD(zbpg_unused_list);
static unsigned long zcache_zbpg_unused_list_count;
/* protects the unused page list */
static DEFINE_SPINLOCK(zbpg_unused_list_spinlock);
static atomic_t zcache_zbud_curr_raw_pages;
static atomic_t zcache_zbud_curr_zpages;
static unsigned long zcache_zbud_curr_zbytes;
static unsigned long zcache_zbud_cumul_zpages;
static unsigned long zcache_zbud_cumul_zbytes;
static unsigned long zcache_compress_poor;
static unsigned long zcache_mean_compress_poor;
/* forward references */
static void *zcache_get_free_page(void);
static void zcache_free_page(void *p);
/*
* zbud helper functions
*/
static inline unsigned zbud_max_buddy_size(void)
{
return MAX_CHUNK << CHUNK_SHIFT;
}
static inline unsigned zbud_size_to_chunks(unsigned size)
{
BUG_ON(size == 0 || size > zbud_max_buddy_size());
return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
}
static inline int zbud_budnum(struct zbud_hdr *zh)
{
unsigned offset = (unsigned long)zh & (PAGE_SIZE - 1);
struct zbud_page *zbpg = NULL;
unsigned budnum = -1U;
int i;
for (i = 0; i < ZBUD_MAX_BUDS; i++)
if (offset == offsetof(typeof(*zbpg), buddy[i])) {
budnum = i;
break;
}
BUG_ON(budnum == -1U);
return budnum;
}
static char *zbud_data(struct zbud_hdr *zh, unsigned size)
{
struct zbud_page *zbpg;
char *p;
unsigned budnum;
ASSERT_SENTINEL(zh, ZBH);
budnum = zbud_budnum(zh);
BUG_ON(size == 0 || size > zbud_max_buddy_size());
zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
ASSERT_SPINLOCK(&zbpg->lock);
p = (char *)zbpg;
if (budnum == 0)
p += ((sizeof(struct zbud_page) + CHUNK_SIZE - 1) &
CHUNK_MASK);
else if (budnum == 1)
p += PAGE_SIZE - ((size + CHUNK_SIZE - 1) & CHUNK_MASK);
return p;
}
/*
* zbud raw page management
*/
static struct zbud_page *zbud_alloc_raw_page(void)
{
struct zbud_page *zbpg = NULL;
struct zbud_hdr *zh0, *zh1;
bool recycled = 0;
/* if any pages on the zbpg list, use one */
spin_lock(&zbpg_unused_list_spinlock);
if (!list_empty(&zbpg_unused_list)) {
zbpg = list_first_entry(&zbpg_unused_list,
struct zbud_page, bud_list);
list_del_init(&zbpg->bud_list);
zcache_zbpg_unused_list_count--;
recycled = 1;
}
spin_unlock(&zbpg_unused_list_spinlock);
if (zbpg == NULL)
/* none on zbpg list, try to get a kernel page */
zbpg = zcache_get_free_page();
if (likely(zbpg != NULL)) {
INIT_LIST_HEAD(&zbpg->bud_list);
zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
spin_lock_init(&zbpg->lock);
if (recycled) {
ASSERT_INVERTED_SENTINEL(zbpg, ZBPG);
SET_SENTINEL(zbpg, ZBPG);
BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
} else {
atomic_inc(&zcache_zbud_curr_raw_pages);
INIT_LIST_HEAD(&zbpg->bud_list);
SET_SENTINEL(zbpg, ZBPG);
zh0->size = 0; zh1->size = 0;
tmem_oid_set_invalid(&zh0->oid);
tmem_oid_set_invalid(&zh1->oid);
}
}
return zbpg;
}
static void zbud_free_raw_page(struct zbud_page *zbpg)
{
struct zbud_hdr *zh0 = &zbpg->buddy[0], *zh1 = &zbpg->buddy[1];
ASSERT_SENTINEL(zbpg, ZBPG);
BUG_ON(!list_empty(&zbpg->bud_list));
ASSERT_SPINLOCK(&zbpg->lock);
BUG_ON(zh0->size != 0 || tmem_oid_valid(&zh0->oid));
BUG_ON(zh1->size != 0 || tmem_oid_valid(&zh1->oid));
INVERT_SENTINEL(zbpg, ZBPG);
spin_unlock(&zbpg->lock);
spin_lock(&zbpg_unused_list_spinlock);
list_add(&zbpg->bud_list, &zbpg_unused_list);
zcache_zbpg_unused_list_count++;
spin_unlock(&zbpg_unused_list_spinlock);
}
/*
* core zbud handling routines
*/
static unsigned zbud_free(struct zbud_hdr *zh)
{
unsigned size;
ASSERT_SENTINEL(zh, ZBH);
BUG_ON(!tmem_oid_valid(&zh->oid));
size = zh->size;
BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
zh->size = 0;
tmem_oid_set_invalid(&zh->oid);
INVERT_SENTINEL(zh, ZBH);
zcache_zbud_curr_zbytes -= size;
atomic_dec(&zcache_zbud_curr_zpages);
return size;
}
static void zbud_free_and_delist(struct zbud_hdr *zh)
{
unsigned chunks;
struct zbud_hdr *zh_other;
unsigned budnum = zbud_budnum(zh), size;
struct zbud_page *zbpg =
container_of(zh, struct zbud_page, buddy[budnum]);
spin_lock(&zbpg->lock);
if (list_empty(&zbpg->bud_list)) {
/* ignore zombie page... see zbud_evict_pages() */
spin_unlock(&zbpg->lock);
return;
}
size = zbud_free(zh);
ASSERT_SPINLOCK(&zbpg->lock);
zh_other = &zbpg->buddy[(budnum == 0) ? 1 : 0];
if (zh_other->size == 0) { /* was unbuddied: unlist and free */
chunks = zbud_size_to_chunks(size) ;
spin_lock(&zbud_budlists_spinlock);
BUG_ON(list_empty(&zbud_unbuddied[chunks].list));
list_del_init(&zbpg->bud_list);
zbud_unbuddied[chunks].count--;
spin_unlock(&zbud_budlists_spinlock);
zbud_free_raw_page(zbpg);
} else { /* was buddied: move remaining buddy to unbuddied list */
chunks = zbud_size_to_chunks(zh_other->size) ;
spin_lock(&zbud_budlists_spinlock);
list_del_init(&zbpg->bud_list);
zcache_zbud_buddied_count--;
list_add_tail(&zbpg->bud_list, &zbud_unbuddied[chunks].list);
zbud_unbuddied[chunks].count++;
spin_unlock(&zbud_budlists_spinlock);
spin_unlock(&zbpg->lock);
}
}
static struct zbud_hdr *zbud_create(uint16_t client_id, uint16_t pool_id,
struct tmem_oid *oid,
uint32_t index, struct page *page,
void *cdata, unsigned size)
{
struct zbud_hdr *zh0, *zh1, *zh = NULL;
struct zbud_page *zbpg = NULL, *ztmp;
unsigned nchunks;
char *to;
int i, found_good_buddy = 0;
nchunks = zbud_size_to_chunks(size) ;
for (i = MAX_CHUNK - nchunks + 1; i > 0; i--) {
spin_lock(&zbud_budlists_spinlock);
if (!list_empty(&zbud_unbuddied[i].list)) {
list_for_each_entry_safe(zbpg, ztmp,
&zbud_unbuddied[i].list, bud_list) {
if (spin_trylock(&zbpg->lock)) {
found_good_buddy = i;
goto found_unbuddied;
}
}
}
spin_unlock(&zbud_budlists_spinlock);
}
/* didn't find a good buddy, try allocating a new page */
zbpg = zbud_alloc_raw_page();
if (unlikely(zbpg == NULL))
goto out;
/* ok, have a page, now compress the data before taking locks */
spin_lock(&zbud_budlists_spinlock);
spin_lock(&zbpg->lock);
list_add_tail(&zbpg->bud_list, &zbud_unbuddied[nchunks].list);
zbud_unbuddied[nchunks].count++;
zh = &zbpg->buddy[0];
goto init_zh;
found_unbuddied:
ASSERT_SPINLOCK(&zbpg->lock);
zh0 = &zbpg->buddy[0]; zh1 = &zbpg->buddy[1];
BUG_ON(!((zh0->size == 0) ^ (zh1->size == 0)));
if (zh0->size != 0) { /* buddy0 in use, buddy1 is vacant */
ASSERT_SENTINEL(zh0, ZBH);
zh = zh1;
} else if (zh1->size != 0) { /* buddy1 in use, buddy0 is vacant */
ASSERT_SENTINEL(zh1, ZBH);
zh = zh0;
} else
BUG();
list_del_init(&zbpg->bud_list);
zbud_unbuddied[found_good_buddy].count--;
list_add_tail(&zbpg->bud_list, &zbud_buddied_list);
zcache_zbud_buddied_count++;
init_zh:
SET_SENTINEL(zh, ZBH);
zh->size = size;
zh->index = index;
zh->oid = *oid;
zh->pool_id = pool_id;
zh->client_id = client_id;
to = zbud_data(zh, size);
memcpy(to, cdata, size);
spin_unlock(&zbpg->lock);
spin_unlock(&zbud_budlists_spinlock);
zbud_cumul_chunk_counts[nchunks]++;
atomic_inc(&zcache_zbud_curr_zpages);
zcache_zbud_cumul_zpages++;
zcache_zbud_curr_zbytes += size;
zcache_zbud_cumul_zbytes += size;
out:
return zh;
}
static int zbud_decompress(struct page *page, struct zbud_hdr *zh)
{
struct zbud_page *zbpg;
unsigned budnum = zbud_budnum(zh);
size_t out_len = PAGE_SIZE;
char *to_va, *from_va;
unsigned size;
int ret = 0;
zbpg = container_of(zh, struct zbud_page, buddy[budnum]);
spin_lock(&zbpg->lock);
if (list_empty(&zbpg->bud_list)) {
/* ignore zombie page... see zbud_evict_pages() */
ret = -EINVAL;
goto out;
}
ASSERT_SENTINEL(zh, ZBH);
BUG_ON(zh->size == 0 || zh->size > zbud_max_buddy_size());
to_va = kmap_atomic(page, KM_USER0);
size = zh->size;
from_va = zbud_data(zh, size);
ret = lzo1x_decompress_safe(from_va, size, to_va, &out_len);
BUG_ON(ret != LZO_E_OK);
BUG_ON(out_len != PAGE_SIZE);
kunmap_atomic(to_va, KM_USER0);
out:
spin_unlock(&zbpg->lock);
return ret;
}
/*
* The following routines handle shrinking of ephemeral pages by evicting
* pages "least valuable" first.
*/
static unsigned long zcache_evicted_raw_pages;
static unsigned long zcache_evicted_buddied_pages;
static unsigned long zcache_evicted_unbuddied_pages;
static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id,
uint16_t poolid);
static void zcache_put_pool(struct tmem_pool *pool);
/*
* Flush and free all zbuds in a zbpg, then free the pageframe
*/
static void zbud_evict_zbpg(struct zbud_page *zbpg)
{
struct zbud_hdr *zh;
int i, j;
uint32_t pool_id[ZBUD_MAX_BUDS], client_id[ZBUD_MAX_BUDS];
uint32_t index[ZBUD_MAX_BUDS];
struct tmem_oid oid[ZBUD_MAX_BUDS];
struct tmem_pool *pool;
ASSERT_SPINLOCK(&zbpg->lock);
BUG_ON(!list_empty(&zbpg->bud_list));
for (i = 0, j = 0; i < ZBUD_MAX_BUDS; i++) {
zh = &zbpg->buddy[i];
if (zh->size) {
client_id[j] = zh->client_id;
pool_id[j] = zh->pool_id;
oid[j] = zh->oid;
index[j] = zh->index;
j++;
zbud_free(zh);
}
}
spin_unlock(&zbpg->lock);
for (i = 0; i < j; i++) {
pool = zcache_get_pool_by_id(client_id[i], pool_id[i]);
if (pool != NULL) {
tmem_flush_page(pool, &oid[i], index[i]);
zcache_put_pool(pool);
}
}
ASSERT_SENTINEL(zbpg, ZBPG);
spin_lock(&zbpg->lock);
zbud_free_raw_page(zbpg);
}
/*
* Free nr pages. This code is funky because we want to hold the locks
* protecting various lists for as short a time as possible, and in some
* circumstances the list may change asynchronously when the list lock is
* not held. In some cases we also trylock not only to avoid waiting on a
* page in use by another cpu, but also to avoid potential deadlock due to
* lock inversion.
*/
static void zbud_evict_pages(int nr)
{
struct zbud_page *zbpg;
int i;
/* first try freeing any pages on unused list */
retry_unused_list:
spin_lock_bh(&zbpg_unused_list_spinlock);
if (!list_empty(&zbpg_unused_list)) {
/* can't walk list here, since it may change when unlocked */
zbpg = list_first_entry(&zbpg_unused_list,
struct zbud_page, bud_list);
list_del_init(&zbpg->bud_list);
zcache_zbpg_unused_list_count--;
atomic_dec(&zcache_zbud_curr_raw_pages);
spin_unlock_bh(&zbpg_unused_list_spinlock);
zcache_free_page(zbpg);
zcache_evicted_raw_pages++;
if (--nr <= 0)
goto out;
goto retry_unused_list;
}
spin_unlock_bh(&zbpg_unused_list_spinlock);
/* now try freeing unbuddied pages, starting with least space avail */
for (i = 0; i < MAX_CHUNK; i++) {
retry_unbud_list_i:
spin_lock_bh(&zbud_budlists_spinlock);
if (list_empty(&zbud_unbuddied[i].list)) {
spin_unlock_bh(&zbud_budlists_spinlock);
continue;
}
list_for_each_entry(zbpg, &zbud_unbuddied[i].list, bud_list) {
if (unlikely(!spin_trylock(&zbpg->lock)))
continue;
list_del_init(&zbpg->bud_list);
zbud_unbuddied[i].count--;
spin_unlock(&zbud_budlists_spinlock);
zcache_evicted_unbuddied_pages++;
/* want budlists unlocked when doing zbpg eviction */
zbud_evict_zbpg(zbpg);
local_bh_enable();
if (--nr <= 0)
goto out;
goto retry_unbud_list_i;
}
spin_unlock_bh(&zbud_budlists_spinlock);
}
/* as a last resort, free buddied pages */
retry_bud_list:
spin_lock_bh(&zbud_budlists_spinlock);
if (list_empty(&zbud_buddied_list)) {
spin_unlock_bh(&zbud_budlists_spinlock);
goto out;
}
list_for_each_entry(zbpg, &zbud_buddied_list, bud_list) {
if (unlikely(!spin_trylock(&zbpg->lock)))
continue;
list_del_init(&zbpg->bud_list);
zcache_zbud_buddied_count--;
spin_unlock(&zbud_budlists_spinlock);
zcache_evicted_buddied_pages++;
/* want budlists unlocked when doing zbpg eviction */
zbud_evict_zbpg(zbpg);
local_bh_enable();
if (--nr <= 0)
goto out;
goto retry_bud_list;
}
spin_unlock_bh(&zbud_budlists_spinlock);
out:
return;
}
static void zbud_init(void)
{
int i;
INIT_LIST_HEAD(&zbud_buddied_list);
zcache_zbud_buddied_count = 0;
for (i = 0; i < NCHUNKS; i++) {
INIT_LIST_HEAD(&zbud_unbuddied[i].list);
zbud_unbuddied[i].count = 0;
}
}
#ifdef CONFIG_SYSFS
/*
* These sysfs routines show a nice distribution of how many zbpg's are
* currently (and have ever been placed) in each unbuddied list. It's fun
* to watch but can probably go away before final merge.
*/
static int zbud_show_unbuddied_list_counts(char *buf)
{
int i;
char *p = buf;
for (i = 0; i < NCHUNKS; i++)
p += sprintf(p, "%u ", zbud_unbuddied[i].count);
return p - buf;
}
static int zbud_show_cumul_chunk_counts(char *buf)
{
unsigned long i, chunks = 0, total_chunks = 0, sum_total_chunks = 0;
unsigned long total_chunks_lte_21 = 0, total_chunks_lte_32 = 0;
unsigned long total_chunks_lte_42 = 0;
char *p = buf;
for (i = 0; i < NCHUNKS; i++) {
p += sprintf(p, "%lu ", zbud_cumul_chunk_counts[i]);
chunks += zbud_cumul_chunk_counts[i];
total_chunks += zbud_cumul_chunk_counts[i];
sum_total_chunks += i * zbud_cumul_chunk_counts[i];
if (i == 21)
total_chunks_lte_21 = total_chunks;
if (i == 32)
total_chunks_lte_32 = total_chunks;
if (i == 42)
total_chunks_lte_42 = total_chunks;
}
p += sprintf(p, "<=21:%lu <=32:%lu <=42:%lu, mean:%lu\n",
total_chunks_lte_21, total_chunks_lte_32, total_chunks_lte_42,
chunks == 0 ? 0 : sum_total_chunks / chunks);
return p - buf;
}
#endif
/**********
* This "zv" PAM implementation combines the TLSF-based xvMalloc
* with lzo1x compression to maximize the amount of data that can
* be packed into a physical page.
*
* Zv represents a PAM page with the index and object (plus a "size" value
* necessary for decompression) immediately preceding the compressed data.
*/
#define ZVH_SENTINEL 0x43214321
struct zv_hdr {
uint32_t pool_id;
struct tmem_oid oid;
uint32_t index;
DECL_SENTINEL
};
/* rudimentary policy limits */
/* total number of persistent pages may not exceed this percentage */
static unsigned int zv_page_count_policy_percent = 75;
/*
* byte count defining poor compression; pages with greater zsize will be
* rejected
*/
static unsigned int zv_max_zsize = (PAGE_SIZE / 8) * 7;
/*
* byte count defining poor *mean* compression; pages with greater zsize
* will be rejected until sufficient better-compressed pages are accepted
* driving the mean below this threshold
*/
static unsigned int zv_max_mean_zsize = (PAGE_SIZE / 8) * 5;
static atomic_t zv_curr_dist_counts[NCHUNKS];
static atomic_t zv_cumul_dist_counts[NCHUNKS];
static struct zv_hdr *zv_create(struct xv_pool *xvpool, uint32_t pool_id,
struct tmem_oid *oid, uint32_t index,
void *cdata, unsigned clen)
{
struct page *page;
struct zv_hdr *zv = NULL;
uint32_t offset;
int alloc_size = clen + sizeof(struct zv_hdr);
int chunks = (alloc_size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
int ret;
BUG_ON(!irqs_disabled());
BUG_ON(chunks >= NCHUNKS);
ret = xv_malloc(xvpool, alloc_size,
&page, &offset, ZCACHE_GFP_MASK);
if (unlikely(ret))
goto out;
atomic_inc(&zv_curr_dist_counts[chunks]);
atomic_inc(&zv_cumul_dist_counts[chunks]);
zv = kmap_atomic(page, KM_USER0) + offset;
zv->index = index;
zv->oid = *oid;
zv->pool_id = pool_id;
SET_SENTINEL(zv, ZVH);
memcpy((char *)zv + sizeof(struct zv_hdr), cdata, clen);
kunmap_atomic(zv, KM_USER0);
out:
return zv;
}
static void zv_free(struct xv_pool *xvpool, struct zv_hdr *zv)
{
unsigned long flags;
struct page *page;
uint32_t offset;
uint16_t size = xv_get_object_size(zv);
int chunks = (size + (CHUNK_SIZE - 1)) >> CHUNK_SHIFT;
ASSERT_SENTINEL(zv, ZVH);
BUG_ON(chunks >= NCHUNKS);
atomic_dec(&zv_curr_dist_counts[chunks]);
size -= sizeof(*zv);
BUG_ON(size == 0);
INVERT_SENTINEL(zv, ZVH);
page = virt_to_page(zv);
offset = (unsigned long)zv & ~PAGE_MASK;
local_irq_save(flags);
xv_free(xvpool, page, offset);
local_irq_restore(flags);
}
static void zv_decompress(struct page *page, struct zv_hdr *zv)
{
size_t clen = PAGE_SIZE;
char *to_va;
unsigned size;
int ret;
ASSERT_SENTINEL(zv, ZVH);
size = xv_get_object_size(zv) - sizeof(*zv);
BUG_ON(size == 0);
to_va = kmap_atomic(page, KM_USER0);
ret = lzo1x_decompress_safe((char *)zv + sizeof(*zv),
size, to_va, &clen);
kunmap_atomic(to_va, KM_USER0);
BUG_ON(ret != LZO_E_OK);
BUG_ON(clen != PAGE_SIZE);
}
#ifdef CONFIG_SYSFS
/*
* show a distribution of compression stats for zv pages.
*/
static int zv_curr_dist_counts_show(char *buf)
{
unsigned long i, n, chunks = 0, sum_total_chunks = 0;
char *p = buf;
for (i = 0; i < NCHUNKS; i++) {
n = atomic_read(&zv_curr_dist_counts[i]);
p += sprintf(p, "%lu ", n);
chunks += n;
sum_total_chunks += i * n;
}
p += sprintf(p, "mean:%lu\n",
chunks == 0 ? 0 : sum_total_chunks / chunks);
return p - buf;
}
static int zv_cumul_dist_counts_show(char *buf)
{
unsigned long i, n, chunks = 0, sum_total_chunks = 0;
char *p = buf;
for (i = 0; i < NCHUNKS; i++) {
n = atomic_read(&zv_cumul_dist_counts[i]);
p += sprintf(p, "%lu ", n);
chunks += n;
sum_total_chunks += i * n;
}
p += sprintf(p, "mean:%lu\n",
chunks == 0 ? 0 : sum_total_chunks / chunks);
return p - buf;
}
/*
* setting zv_max_zsize via sysfs causes all persistent (e.g. swap)
* pages that don't compress to less than this value (including metadata
* overhead) to be rejected. We don't allow the value to get too close
* to PAGE_SIZE.
*/
static ssize_t zv_max_zsize_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%u\n", zv_max_zsize);
}
static ssize_t zv_max_zsize_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7))
return -EINVAL;
zv_max_zsize = val;
return count;
}
/*
* setting zv_max_mean_zsize via sysfs causes all persistent (e.g. swap)
* pages that don't compress to less than this value (including metadata
* overhead) to be rejected UNLESS the mean compression is also smaller
* than this value. In other words, we are load-balancing-by-zsize the
* accepted pages. Again, we don't allow the value to get too close
* to PAGE_SIZE.
*/
static ssize_t zv_max_mean_zsize_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%u\n", zv_max_mean_zsize);
}
static ssize_t zv_max_mean_zsize_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err || (val == 0) || (val > (PAGE_SIZE / 8) * 7))
return -EINVAL;
zv_max_mean_zsize = val;
return count;
}
/*
* setting zv_page_count_policy_percent via sysfs sets an upper bound of
* persistent (e.g. swap) pages that will be retained according to:
* (zv_page_count_policy_percent * totalram_pages) / 100)
* when that limit is reached, further puts will be rejected (until
* some pages have been flushed). Note that, due to compression,
* this number may exceed 100; it defaults to 75 and we set an
* arbitary limit of 150. A poor choice will almost certainly result
* in OOM's, so this value should only be changed prudently.
*/
static ssize_t zv_page_count_policy_percent_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
return sprintf(buf, "%u\n", zv_page_count_policy_percent);
}
static ssize_t zv_page_count_policy_percent_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
unsigned long val;
int err;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
err = kstrtoul(buf, 10, &val);
if (err || (val == 0) || (val > 150))
return -EINVAL;
zv_page_count_policy_percent = val;
return count;
}
static struct kobj_attribute zcache_zv_max_zsize_attr = {
.attr = { .name = "zv_max_zsize", .mode = 0644 },
.show = zv_max_zsize_show,
.store = zv_max_zsize_store,
};
static struct kobj_attribute zcache_zv_max_mean_zsize_attr = {
.attr = { .name = "zv_max_mean_zsize", .mode = 0644 },
.show = zv_max_mean_zsize_show,
.store = zv_max_mean_zsize_store,
};
static struct kobj_attribute zcache_zv_page_count_policy_percent_attr = {
.attr = { .name = "zv_page_count_policy_percent",
.mode = 0644 },
.show = zv_page_count_policy_percent_show,
.store = zv_page_count_policy_percent_store,
};
#endif
/*
* zcache core code starts here
*/
/* useful stats not collected by cleancache or frontswap */
static unsigned long zcache_flush_total;
static unsigned long zcache_flush_found;
static unsigned long zcache_flobj_total;
static unsigned long zcache_flobj_found;
static unsigned long zcache_failed_eph_puts;
static unsigned long zcache_failed_pers_puts;
/*
* Tmem operations assume the poolid implies the invoking client.
* Zcache only has one client (the kernel itself): LOCAL_CLIENT.
* RAMster has each client numbered by cluster node, and a KVM version
* of zcache would have one client per guest and each client might
* have a poolid==N.
*/
static struct tmem_pool *zcache_get_pool_by_id(uint16_t cli_id, uint16_t poolid)
{
struct tmem_pool *pool = NULL;
struct zcache_client *cli = NULL;
if (cli_id == LOCAL_CLIENT)
cli = &zcache_host;
else {
if (cli_id >= MAX_CLIENTS)
goto out;
cli = &zcache_clients[cli_id];
if (cli == NULL)
goto out;
atomic_inc(&cli->refcount);
}
if (poolid < MAX_POOLS_PER_CLIENT) {
pool = cli->tmem_pools[poolid];
if (pool != NULL)
atomic_inc(&pool->refcount);
}
out:
return pool;
}
static void zcache_put_pool(struct tmem_pool *pool)
{
struct zcache_client *cli = NULL;
if (pool == NULL)
BUG();
cli = pool->client;
atomic_dec(&pool->refcount);
atomic_dec(&cli->refcount);
}
int zcache_new_client(uint16_t cli_id)
{
struct zcache_client *cli = NULL;
int ret = -1;
if (cli_id == LOCAL_CLIENT)
cli = &zcache_host;
else if ((unsigned int)cli_id < MAX_CLIENTS)
cli = &zcache_clients[cli_id];
if (cli == NULL)
goto out;
if (cli->allocated)
goto out;
cli->allocated = 1;
#ifdef CONFIG_FRONTSWAP
cli->xvpool = xv_create_pool();
if (cli->xvpool == NULL)
goto out;
#endif
ret = 0;
out:
return ret;
}
/* counters for debugging */
static unsigned long zcache_failed_get_free_pages;
static unsigned long zcache_failed_alloc;
static unsigned long zcache_put_to_flush;
/*
* for now, used named slabs so can easily track usage; later can
* either just use kmalloc, or perhaps add a slab-like allocator
* to more carefully manage total memory utilization
*/
static struct kmem_cache *zcache_objnode_cache;
static struct kmem_cache *zcache_obj_cache;
static atomic_t zcache_curr_obj_count = ATOMIC_INIT(0);
static unsigned long zcache_curr_obj_count_max;
static atomic_t zcache_curr_objnode_count = ATOMIC_INIT(0);
static unsigned long zcache_curr_objnode_count_max;
/*
* to avoid memory allocation recursion (e.g. due to direct reclaim), we
* preload all necessary data structures so the hostops callbacks never
* actually do a malloc
*/
struct zcache_preload {
void *page;
struct tmem_obj *obj;
int nr;
struct tmem_objnode *objnodes[OBJNODE_TREE_MAX_PATH];
};
static DEFINE_PER_CPU(struct zcache_preload, zcache_preloads) = { 0, };
static int zcache_do_preload(struct tmem_pool *pool)
{
struct zcache_preload *kp;
struct tmem_objnode *objnode;
struct tmem_obj *obj;
void *page;
int ret = -ENOMEM;
if (unlikely(zcache_objnode_cache == NULL))
goto out;
if (unlikely(zcache_obj_cache == NULL))
goto out;
preempt_disable();
kp = &__get_cpu_var(zcache_preloads);
while (kp->nr < ARRAY_SIZE(kp->objnodes)) {
preempt_enable_no_resched();
objnode = kmem_cache_alloc(zcache_objnode_cache,
ZCACHE_GFP_MASK);
if (unlikely(objnode == NULL)) {
zcache_failed_alloc++;
goto out;
}
preempt_disable();
kp = &__get_cpu_var(zcache_preloads);
if (kp->nr < ARRAY_SIZE(kp->objnodes))
kp->objnodes[kp->nr++] = objnode;
else
kmem_cache_free(zcache_objnode_cache, objnode);
}
preempt_enable_no_resched();
obj = kmem_cache_alloc(zcache_obj_cache, ZCACHE_GFP_MASK);
if (unlikely(obj == NULL)) {
zcache_failed_alloc++;
goto out;
}
page = (void *)__get_free_page(ZCACHE_GFP_MASK);
if (unlikely(page == NULL)) {
zcache_failed_get_free_pages++;
kmem_cache_free(zcache_obj_cache, obj);
goto out;
}
preempt_disable();
kp = &__get_cpu_var(zcache_preloads);
if (kp->obj == NULL)
kp->obj = obj;
else
kmem_cache_free(zcache_obj_cache, obj);
if (kp->page == NULL)
kp->page = page;
else
free_page((unsigned long)page);
ret = 0;
out:
return ret;
}
static void *zcache_get_free_page(void)
{
struct zcache_preload *kp;
void *page;
kp = &__get_cpu_var(zcache_preloads);
page = kp->page;
BUG_ON(page == NULL);
kp->page = NULL;
return page;
}
static void zcache_free_page(void *p)
{
free_page((unsigned long)p);
}
/*
* zcache implementation for tmem host ops
*/
static struct tmem_objnode *zcache_objnode_alloc(struct tmem_pool *pool)
{
struct tmem_objnode *objnode = NULL;
unsigned long count;
struct zcache_preload *kp;
kp = &__get_cpu_var(zcache_preloads);
if (kp->nr <= 0)
goto out;
objnode = kp->objnodes[kp->nr - 1];
BUG_ON(objnode == NULL);
kp->objnodes[kp->nr - 1] = NULL;
kp->nr--;
count = atomic_inc_return(&zcache_curr_objnode_count);
if (count > zcache_curr_objnode_count_max)
zcache_curr_objnode_count_max = count;
out:
return objnode;
}
static void zcache_objnode_free(struct tmem_objnode *objnode,
struct tmem_pool *pool)
{
atomic_dec(&zcache_curr_objnode_count);
BUG_ON(atomic_read(&zcache_curr_objnode_count) < 0);
kmem_cache_free(zcache_objnode_cache, objnode);
}
static struct tmem_obj *zcache_obj_alloc(struct tmem_pool *pool)
{
struct tmem_obj *obj = NULL;
unsigned long count;
struct zcache_preload *kp;
kp = &__get_cpu_var(zcache_preloads);
obj = kp->obj;
BUG_ON(obj == NULL);
kp->obj = NULL;
count = atomic_inc_return(&zcache_curr_obj_count);
if (count > zcache_curr_obj_count_max)
zcache_curr_obj_count_max = count;
return obj;
}
static void zcache_obj_free(struct tmem_obj *obj, struct tmem_pool *pool)
{
atomic_dec(&zcache_curr_obj_count);
BUG_ON(atomic_read(&zcache_curr_obj_count) < 0);
kmem_cache_free(zcache_obj_cache, obj);
}
static struct tmem_hostops zcache_hostops = {
.obj_alloc = zcache_obj_alloc,
.obj_free = zcache_obj_free,
.objnode_alloc = zcache_objnode_alloc,
.objnode_free = zcache_objnode_free,
};
/*
* zcache implementations for PAM page descriptor ops
*/
static atomic_t zcache_curr_eph_pampd_count = ATOMIC_INIT(0);
static unsigned long zcache_curr_eph_pampd_count_max;
static atomic_t zcache_curr_pers_pampd_count = ATOMIC_INIT(0);
static unsigned long zcache_curr_pers_pampd_count_max;
/* forward reference */
static int zcache_compress(struct page *from, void **out_va, size_t *out_len);
static void *zcache_pampd_create(char *data, size_t size, bool raw, int eph,
struct tmem_pool *pool, struct tmem_oid *oid,
uint32_t index)
{
void *pampd = NULL, *cdata;
size_t clen;
int ret;
unsigned long count;
struct page *page = (struct page *)(data);
struct zcache_client *cli = pool->client;
uint16_t client_id = get_client_id_from_client(cli);
unsigned long zv_mean_zsize;
unsigned long curr_pers_pampd_count;
u64 total_zsize;
if (eph) {
ret = zcache_compress(page, &cdata, &clen);
if (ret == 0)
goto out;
if (clen == 0 || clen > zbud_max_buddy_size()) {
zcache_compress_poor++;
goto out;
}
pampd = (void *)zbud_create(client_id, pool->pool_id, oid,
index, page, cdata, clen);
if (pampd != NULL) {
count = atomic_inc_return(&zcache_curr_eph_pampd_count);
if (count > zcache_curr_eph_pampd_count_max)
zcache_curr_eph_pampd_count_max = count;
}
} else {
curr_pers_pampd_count =
atomic_read(&zcache_curr_pers_pampd_count);
if (curr_pers_pampd_count >
(zv_page_count_policy_percent * totalram_pages) / 100)
goto out;
ret = zcache_compress(page, &cdata, &clen);
if (ret == 0)
goto out;
/* reject if compression is too poor */
if (clen > zv_max_zsize) {
zcache_compress_poor++;
goto out;
}
/* reject if mean compression is too poor */
if ((clen > zv_max_mean_zsize) && (curr_pers_pampd_count > 0)) {
total_zsize = xv_get_total_size_bytes(cli->xvpool);
zv_mean_zsize = div_u64(total_zsize,
curr_pers_pampd_count);
if (zv_mean_zsize > zv_max_mean_zsize) {
zcache_mean_compress_poor++;
goto out;
}
}
pampd = (void *)zv_create(cli->xvpool, pool->pool_id,
oid, index, cdata, clen);
if (pampd == NULL)
goto out;
count = atomic_inc_return(&zcache_curr_pers_pampd_count);
if (count > zcache_curr_pers_pampd_count_max)
zcache_curr_pers_pampd_count_max = count;
}
out:
return pampd;
}
/*
* fill the pageframe corresponding to the struct page with the data
* from the passed pampd
*/
static int zcache_pampd_get_data(char *data, size_t *bufsize, bool raw,
void *pampd, struct tmem_pool *pool,
struct tmem_oid *oid, uint32_t index)
{
int ret = 0;
BUG_ON(is_ephemeral(pool));
zv_decompress((struct page *)(data), pampd);
return ret;
}
/*
* fill the pageframe corresponding to the struct page with the data
* from the passed pampd
*/
static int zcache_pampd_get_data_and_free(char *data, size_t *bufsize, bool raw,
void *pampd, struct tmem_pool *pool,
struct tmem_oid *oid, uint32_t index)
{
int ret = 0;
BUG_ON(!is_ephemeral(pool));
zbud_decompress((struct page *)(data), pampd);
zbud_free_and_delist((struct zbud_hdr *)pampd);
atomic_dec(&zcache_curr_eph_pampd_count);
return ret;
}
/*
* free the pampd and remove it from any zcache lists
* pampd must no longer be pointed to from any tmem data structures!
*/
static void zcache_pampd_free(void *pampd, struct tmem_pool *pool,
struct tmem_oid *oid, uint32_t index)
{
struct zcache_client *cli = pool->client;
if (is_ephemeral(pool)) {
zbud_free_and_delist((struct zbud_hdr *)pampd);
atomic_dec(&zcache_curr_eph_pampd_count);
BUG_ON(atomic_read(&zcache_curr_eph_pampd_count) < 0);
} else {
zv_free(cli->xvpool, (struct zv_hdr *)pampd);
atomic_dec(&zcache_curr_pers_pampd_count);
BUG_ON(atomic_read(&zcache_curr_pers_pampd_count) < 0);
}
}
static void zcache_pampd_free_obj(struct tmem_pool *pool, struct tmem_obj *obj)
{
}
static void zcache_pampd_new_obj(struct tmem_obj *obj)
{
}
static int zcache_pampd_replace_in_obj(void *pampd, struct tmem_obj *obj)
{
return -1;
}
static bool zcache_pampd_is_remote(void *pampd)
{
return 0;
}
static struct tmem_pamops zcache_pamops = {
.create = zcache_pampd_create,
.get_data = zcache_pampd_get_data,
.get_data_and_free = zcache_pampd_get_data_and_free,
.free = zcache_pampd_free,
.free_obj = zcache_pampd_free_obj,
.new_obj = zcache_pampd_new_obj,
.replace_in_obj = zcache_pampd_replace_in_obj,
.is_remote = zcache_pampd_is_remote,
};
/*
* zcache compression/decompression and related per-cpu stuff
*/
#define LZO_WORKMEM_BYTES LZO1X_1_MEM_COMPRESS
#define LZO_DSTMEM_PAGE_ORDER 1
static DEFINE_PER_CPU(unsigned char *, zcache_workmem);
static DEFINE_PER_CPU(unsigned char *, zcache_dstmem);
static int zcache_compress(struct page *from, void **out_va, size_t *out_len)
{
int ret = 0;
unsigned char *dmem = __get_cpu_var(zcache_dstmem);
unsigned char *wmem = __get_cpu_var(zcache_workmem);
char *from_va;
BUG_ON(!irqs_disabled());
if (unlikely(dmem == NULL || wmem == NULL))
goto out; /* no buffer, so can't compress */
from_va = kmap_atomic(from, KM_USER0);
mb();
ret = lzo1x_1_compress(from_va, PAGE_SIZE, dmem, out_len, wmem);
BUG_ON(ret != LZO_E_OK);
*out_va = dmem;
kunmap_atomic(from_va, KM_USER0);
ret = 1;
out:
return ret;
}
static int zcache_cpu_notifier(struct notifier_block *nb,
unsigned long action, void *pcpu)
{
int cpu = (long)pcpu;
struct zcache_preload *kp;
switch (action) {
case CPU_UP_PREPARE:
per_cpu(zcache_dstmem, cpu) = (void *)__get_free_pages(
GFP_KERNEL | __GFP_REPEAT,
LZO_DSTMEM_PAGE_ORDER),
per_cpu(zcache_workmem, cpu) =
kzalloc(LZO1X_MEM_COMPRESS,
GFP_KERNEL | __GFP_REPEAT);
break;
case CPU_DEAD:
case CPU_UP_CANCELED:
free_pages((unsigned long)per_cpu(zcache_dstmem, cpu),
LZO_DSTMEM_PAGE_ORDER);
per_cpu(zcache_dstmem, cpu) = NULL;
kfree(per_cpu(zcache_workmem, cpu));
per_cpu(zcache_workmem, cpu) = NULL;
kp = &per_cpu(zcache_preloads, cpu);
while (kp->nr) {
kmem_cache_free(zcache_objnode_cache,
kp->objnodes[kp->nr - 1]);
kp->objnodes[kp->nr - 1] = NULL;
kp->nr--;
}
if (kp->obj) {
kmem_cache_free(zcache_obj_cache, kp->obj);
kp->obj = NULL;
}
if (kp->page) {
free_page((unsigned long)kp->page);
kp->page = NULL;
}
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block zcache_cpu_notifier_block = {
.notifier_call = zcache_cpu_notifier
};
#ifdef CONFIG_SYSFS
#define ZCACHE_SYSFS_RO(_name) \
static ssize_t zcache_##_name##_show(struct kobject *kobj, \
struct kobj_attribute *attr, char *buf) \
{ \
return sprintf(buf, "%lu\n", zcache_##_name); \
} \
static struct kobj_attribute zcache_##_name##_attr = { \
.attr = { .name = __stringify(_name), .mode = 0444 }, \
.show = zcache_##_name##_show, \
}
#define ZCACHE_SYSFS_RO_ATOMIC(_name) \
static ssize_t zcache_##_name##_show(struct kobject *kobj, \
struct kobj_attribute *attr, char *buf) \
{ \
return sprintf(buf, "%d\n", atomic_read(&zcache_##_name)); \
} \
static struct kobj_attribute zcache_##_name##_attr = { \
.attr = { .name = __stringify(_name), .mode = 0444 }, \
.show = zcache_##_name##_show, \
}
#define ZCACHE_SYSFS_RO_CUSTOM(_name, _func) \
static ssize_t zcache_##_name##_show(struct kobject *kobj, \
struct kobj_attribute *attr, char *buf) \
{ \
return _func(buf); \
} \
static struct kobj_attribute zcache_##_name##_attr = { \
.attr = { .name = __stringify(_name), .mode = 0444 }, \
.show = zcache_##_name##_show, \
}
ZCACHE_SYSFS_RO(curr_obj_count_max);
ZCACHE_SYSFS_RO(curr_objnode_count_max);
ZCACHE_SYSFS_RO(flush_total);
ZCACHE_SYSFS_RO(flush_found);
ZCACHE_SYSFS_RO(flobj_total);
ZCACHE_SYSFS_RO(flobj_found);
ZCACHE_SYSFS_RO(failed_eph_puts);
ZCACHE_SYSFS_RO(failed_pers_puts);
ZCACHE_SYSFS_RO(zbud_curr_zbytes);
ZCACHE_SYSFS_RO(zbud_cumul_zpages);
ZCACHE_SYSFS_RO(zbud_cumul_zbytes);
ZCACHE_SYSFS_RO(zbud_buddied_count);
ZCACHE_SYSFS_RO(zbpg_unused_list_count);
ZCACHE_SYSFS_RO(evicted_raw_pages);
ZCACHE_SYSFS_RO(evicted_unbuddied_pages);
ZCACHE_SYSFS_RO(evicted_buddied_pages);
ZCACHE_SYSFS_RO(failed_get_free_pages);
ZCACHE_SYSFS_RO(failed_alloc);
ZCACHE_SYSFS_RO(put_to_flush);
ZCACHE_SYSFS_RO(compress_poor);
ZCACHE_SYSFS_RO(mean_compress_poor);
ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_raw_pages);
ZCACHE_SYSFS_RO_ATOMIC(zbud_curr_zpages);
ZCACHE_SYSFS_RO_ATOMIC(curr_obj_count);
ZCACHE_SYSFS_RO_ATOMIC(curr_objnode_count);
ZCACHE_SYSFS_RO_CUSTOM(zbud_unbuddied_list_counts,
zbud_show_unbuddied_list_counts);
ZCACHE_SYSFS_RO_CUSTOM(zbud_cumul_chunk_counts,
zbud_show_cumul_chunk_counts);
ZCACHE_SYSFS_RO_CUSTOM(zv_curr_dist_counts,
zv_curr_dist_counts_show);
ZCACHE_SYSFS_RO_CUSTOM(zv_cumul_dist_counts,
zv_cumul_dist_counts_show);
static struct attribute *zcache_attrs[] = {
&zcache_curr_obj_count_attr.attr,
&zcache_curr_obj_count_max_attr.attr,
&zcache_curr_objnode_count_attr.attr,
&zcache_curr_objnode_count_max_attr.attr,
&zcache_flush_total_attr.attr,
&zcache_flobj_total_attr.attr,
&zcache_flush_found_attr.attr,
&zcache_flobj_found_attr.attr,
&zcache_failed_eph_puts_attr.attr,
&zcache_failed_pers_puts_attr.attr,
&zcache_compress_poor_attr.attr,
&zcache_mean_compress_poor_attr.attr,
&zcache_zbud_curr_raw_pages_attr.attr,
&zcache_zbud_curr_zpages_attr.attr,
&zcache_zbud_curr_zbytes_attr.attr,
&zcache_zbud_cumul_zpages_attr.attr,
&zcache_zbud_cumul_zbytes_attr.attr,
&zcache_zbud_buddied_count_attr.attr,
&zcache_zbpg_unused_list_count_attr.attr,
&zcache_evicted_raw_pages_attr.attr,
&zcache_evicted_unbuddied_pages_attr.attr,
&zcache_evicted_buddied_pages_attr.attr,
&zcache_failed_get_free_pages_attr.attr,
&zcache_failed_alloc_attr.attr,
&zcache_put_to_flush_attr.attr,
&zcache_zbud_unbuddied_list_counts_attr.attr,
&zcache_zbud_cumul_chunk_counts_attr.attr,
&zcache_zv_curr_dist_counts_attr.attr,
&zcache_zv_cumul_dist_counts_attr.attr,
&zcache_zv_max_zsize_attr.attr,
&zcache_zv_max_mean_zsize_attr.attr,
&zcache_zv_page_count_policy_percent_attr.attr,
NULL,
};
static struct attribute_group zcache_attr_group = {
.attrs = zcache_attrs,
.name = "zcache",
};
#endif /* CONFIG_SYSFS */
/*
* When zcache is disabled ("frozen"), pools can be created and destroyed,
* but all puts (and thus all other operations that require memory allocation)
* must fail. If zcache is unfrozen, accepts puts, then frozen again,
* data consistency requires all puts while frozen to be converted into
* flushes.
*/
static bool zcache_freeze;
/*
* zcache shrinker interface (only useful for ephemeral pages, so zbud only)
*/
static int shrink_zcache_memory(struct shrinker *shrink,
struct shrink_control *sc)
{
int ret = -1;
int nr = sc->nr_to_scan;
gfp_t gfp_mask = sc->gfp_mask;
if (nr >= 0) {
if (!(gfp_mask & __GFP_FS))
/* does this case really need to be skipped? */
goto out;
zbud_evict_pages(nr);
}
ret = (int)atomic_read(&zcache_zbud_curr_raw_pages);
out:
return ret;
}
static struct shrinker zcache_shrinker = {
.shrink = shrink_zcache_memory,
.seeks = DEFAULT_SEEKS,
};
/*
* zcache shims between cleancache/frontswap ops and tmem
*/
static int zcache_put_page(int cli_id, int pool_id, struct tmem_oid *oidp,
uint32_t index, struct page *page)
{
struct tmem_pool *pool;
int ret = -1;
BUG_ON(!irqs_disabled());
pool = zcache_get_pool_by_id(cli_id, pool_id);
if (unlikely(pool == NULL))
goto out;
if (!zcache_freeze && zcache_do_preload(pool) == 0) {
/* preload does preempt_disable on success */
ret = tmem_put(pool, oidp, index, (char *)(page),
PAGE_SIZE, 0, is_ephemeral(pool));
if (ret < 0) {
if (is_ephemeral(pool))
zcache_failed_eph_puts++;
else
zcache_failed_pers_puts++;
}
zcache_put_pool(pool);
preempt_enable_no_resched();
} else {
zcache_put_to_flush++;
if (atomic_read(&pool->obj_count) > 0)
/* the put fails whether the flush succeeds or not */
(void)tmem_flush_page(pool, oidp, index);
zcache_put_pool(pool);
}
out:
return ret;
}
static int zcache_get_page(int cli_id, int pool_id, struct tmem_oid *oidp,
uint32_t index, struct page *page)
{
struct tmem_pool *pool;
int ret = -1;
unsigned long flags;
size_t size = PAGE_SIZE;
local_irq_save(flags);
pool = zcache_get_pool_by_id(cli_id, pool_id);
if (likely(pool != NULL)) {
if (atomic_read(&pool->obj_count) > 0)
ret = tmem_get(pool, oidp, index, (char *)(page),
&size, 0, is_ephemeral(pool));
zcache_put_pool(pool);
}
local_irq_restore(flags);
return ret;
}
static int zcache_flush_page(int cli_id, int pool_id,
struct tmem_oid *oidp, uint32_t index)
{
struct tmem_pool *pool;
int ret = -1;
unsigned long flags;
local_irq_save(flags);
zcache_flush_total++;
pool = zcache_get_pool_by_id(cli_id, pool_id);
if (likely(pool != NULL)) {
if (atomic_read(&pool->obj_count) > 0)
ret = tmem_flush_page(pool, oidp, index);
zcache_put_pool(pool);
}
if (ret >= 0)
zcache_flush_found++;
local_irq_restore(flags);
return ret;
}
static int zcache_flush_object(int cli_id, int pool_id,
struct tmem_oid *oidp)
{
struct tmem_pool *pool;
int ret = -1;
unsigned long flags;
local_irq_save(flags);
zcache_flobj_total++;
pool = zcache_get_pool_by_id(cli_id, pool_id);
if (likely(pool != NULL)) {
if (atomic_read(&pool->obj_count) > 0)
ret = tmem_flush_object(pool, oidp);
zcache_put_pool(pool);
}
if (ret >= 0)
zcache_flobj_found++;
local_irq_restore(flags);
return ret;
}
static int zcache_destroy_pool(int cli_id, int pool_id)
{
struct tmem_pool *pool = NULL;
struct zcache_client *cli = NULL;
int ret = -1;
if (pool_id < 0)
goto out;
if (cli_id == LOCAL_CLIENT)
cli = &zcache_host;
else if ((unsigned int)cli_id < MAX_CLIENTS)
cli = &zcache_clients[cli_id];
if (cli == NULL)
goto out;
atomic_inc(&cli->refcount);
pool = cli->tmem_pools[pool_id];
if (pool == NULL)
goto out;
cli->tmem_pools[pool_id] = NULL;
/* wait for pool activity on other cpus to quiesce */
while (atomic_read(&pool->refcount) != 0)
;
atomic_dec(&cli->refcount);
local_bh_disable();
ret = tmem_destroy_pool(pool);
local_bh_enable();
kfree(pool);
pr_info("zcache: destroyed pool id=%d, cli_id=%d\n",
pool_id, cli_id);
out:
return ret;
}
static int zcache_new_pool(uint16_t cli_id, uint32_t flags)
{
int poolid = -1;
struct tmem_pool *pool;
struct zcache_client *cli = NULL;
if (cli_id == LOCAL_CLIENT)
cli = &zcache_host;
else if ((unsigned int)cli_id < MAX_CLIENTS)
cli = &zcache_clients[cli_id];
if (cli == NULL)
goto out;
atomic_inc(&cli->refcount);
pool = kmalloc(sizeof(struct tmem_pool), GFP_ATOMIC);
if (pool == NULL) {
pr_info("zcache: pool creation failed: out of memory\n");
goto out;
}
for (poolid = 0; poolid < MAX_POOLS_PER_CLIENT; poolid++)
if (cli->tmem_pools[poolid] == NULL)
break;
if (poolid >= MAX_POOLS_PER_CLIENT) {
pr_info("zcache: pool creation failed: max exceeded\n");
kfree(pool);
poolid = -1;
goto out;
}
atomic_set(&pool->refcount, 0);
pool->client = cli;
pool->pool_id = poolid;
tmem_new_pool(pool, flags);
cli->tmem_pools[poolid] = pool;
pr_info("zcache: created %s tmem pool, id=%d, client=%d\n",
flags & TMEM_POOL_PERSIST ? "persistent" : "ephemeral",
poolid, cli_id);
out:
if (cli != NULL)
atomic_dec(&cli->refcount);
return poolid;
}
/**********
* Two kernel functionalities currently can be layered on top of tmem.
* These are "cleancache" which is used as a second-chance cache for clean
* page cache pages; and "frontswap" which is used for swap pages
* to avoid writes to disk. A generic "shim" is provided here for each
* to translate in-kernel semantics to zcache semantics.
*/
#ifdef CONFIG_CLEANCACHE
static void zcache_cleancache_put_page(int pool_id,
struct cleancache_filekey key,
pgoff_t index, struct page *page)
{
u32 ind = (u32) index;
struct tmem_oid oid = *(struct tmem_oid *)&key;
if (likely(ind == index))
(void)zcache_put_page(LOCAL_CLIENT, pool_id, &oid, index, page);
}
static int zcache_cleancache_get_page(int pool_id,
struct cleancache_filekey key,
pgoff_t index, struct page *page)
{
u32 ind = (u32) index;
struct tmem_oid oid = *(struct tmem_oid *)&key;
int ret = -1;
if (likely(ind == index))
ret = zcache_get_page(LOCAL_CLIENT, pool_id, &oid, index, page);
return ret;
}
static void zcache_cleancache_flush_page(int pool_id,
struct cleancache_filekey key,
pgoff_t index)
{
u32 ind = (u32) index;
struct tmem_oid oid = *(struct tmem_oid *)&key;
if (likely(ind == index))
(void)zcache_flush_page(LOCAL_CLIENT, pool_id, &oid, ind);
}
static void zcache_cleancache_flush_inode(int pool_id,
struct cleancache_filekey key)
{
struct tmem_oid oid = *(struct tmem_oid *)&key;
(void)zcache_flush_object(LOCAL_CLIENT, pool_id, &oid);
}
static void zcache_cleancache_flush_fs(int pool_id)
{
if (pool_id >= 0)
(void)zcache_destroy_pool(LOCAL_CLIENT, pool_id);
}
static int zcache_cleancache_init_fs(size_t pagesize)
{
BUG_ON(sizeof(struct cleancache_filekey) !=
sizeof(struct tmem_oid));
BUG_ON(pagesize != PAGE_SIZE);
return zcache_new_pool(LOCAL_CLIENT, 0);
}
static int zcache_cleancache_init_shared_fs(char *uuid, size_t pagesize)
{
/* shared pools are unsupported and map to private */
BUG_ON(sizeof(struct cleancache_filekey) !=
sizeof(struct tmem_oid));
BUG_ON(pagesize != PAGE_SIZE);
return zcache_new_pool(LOCAL_CLIENT, 0);
}
static struct cleancache_ops zcache_cleancache_ops = {
.put_page = zcache_cleancache_put_page,
.get_page = zcache_cleancache_get_page,
.flush_page = zcache_cleancache_flush_page,
.flush_inode = zcache_cleancache_flush_inode,
.flush_fs = zcache_cleancache_flush_fs,
.init_shared_fs = zcache_cleancache_init_shared_fs,
.init_fs = zcache_cleancache_init_fs
};
struct cleancache_ops zcache_cleancache_register_ops(void)
{
struct cleancache_ops old_ops =
cleancache_register_ops(&zcache_cleancache_ops);
return old_ops;
}
#endif
#ifdef CONFIG_FRONTSWAP
/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
static int zcache_frontswap_poolid = -1;
/*
* Swizzling increases objects per swaptype, increasing tmem concurrency
* for heavy swaploads. Later, larger nr_cpus -> larger SWIZ_BITS
* Setting SWIZ_BITS to 27 basically reconstructs the swap entry from
* frontswap_get_page(), but has side-effects. Hence using 8.
*/
#define SWIZ_BITS 8
#define SWIZ_MASK ((1 << SWIZ_BITS) - 1)
#define _oswiz(_type, _ind) ((_type << SWIZ_BITS) | (_ind & SWIZ_MASK))
#define iswiz(_ind) (_ind >> SWIZ_BITS)
static inline struct tmem_oid oswiz(unsigned type, u32 ind)
{
struct tmem_oid oid = { .oid = { 0 } };
oid.oid[0] = _oswiz(type, ind);
return oid;
}
static int zcache_frontswap_put_page(unsigned type, pgoff_t offset,
struct page *page)
{
u64 ind64 = (u64)offset;
u32 ind = (u32)offset;
struct tmem_oid oid = oswiz(type, ind);
int ret = -1;
unsigned long flags;
BUG_ON(!PageLocked(page));
if (likely(ind64 == ind)) {
local_irq_save(flags);
ret = zcache_put_page(LOCAL_CLIENT, zcache_frontswap_poolid,
&oid, iswiz(ind), page);
local_irq_restore(flags);
}
return ret;
}
/* returns 0 if the page was successfully gotten from frontswap, -1 if
* was not present (should never happen!) */
static int zcache_frontswap_get_page(unsigned type, pgoff_t offset,
struct page *page)
{
u64 ind64 = (u64)offset;
u32 ind = (u32)offset;
struct tmem_oid oid = oswiz(type, ind);
int ret = -1;
BUG_ON(!PageLocked(page));
if (likely(ind64 == ind))
ret = zcache_get_page(LOCAL_CLIENT, zcache_frontswap_poolid,
&oid, iswiz(ind), page);
return ret;
}
/* flush a single page from frontswap */
static void zcache_frontswap_flush_page(unsigned type, pgoff_t offset)
{
u64 ind64 = (u64)offset;
u32 ind = (u32)offset;
struct tmem_oid oid = oswiz(type, ind);
if (likely(ind64 == ind))
(void)zcache_flush_page(LOCAL_CLIENT, zcache_frontswap_poolid,
&oid, iswiz(ind));
}
/* flush all pages from the passed swaptype */
static void zcache_frontswap_flush_area(unsigned type)
{
struct tmem_oid oid;
int ind;
for (ind = SWIZ_MASK; ind >= 0; ind--) {
oid = oswiz(type, ind);
(void)zcache_flush_object(LOCAL_CLIENT,
zcache_frontswap_poolid, &oid);
}
}
static void zcache_frontswap_init(unsigned ignored)
{
/* a single tmem poolid is used for all frontswap "types" (swapfiles) */
if (zcache_frontswap_poolid < 0)
zcache_frontswap_poolid =
zcache_new_pool(LOCAL_CLIENT, TMEM_POOL_PERSIST);
}
static struct frontswap_ops zcache_frontswap_ops = {
.put_page = zcache_frontswap_put_page,
.get_page = zcache_frontswap_get_page,
.flush_page = zcache_frontswap_flush_page,
.flush_area = zcache_frontswap_flush_area,
.init = zcache_frontswap_init
};
struct frontswap_ops zcache_frontswap_register_ops(void)
{
struct frontswap_ops old_ops =
frontswap_register_ops(&zcache_frontswap_ops);
return old_ops;
}
#endif
/*
* zcache initialization
* NOTE FOR NOW zcache MUST BE PROVIDED AS A KERNEL BOOT PARAMETER OR
* NOTHING HAPPENS!
*/
static int zcache_enabled;
static int __init enable_zcache(char *s)
{
zcache_enabled = 1;
return 1;
}
__setup("zcache", enable_zcache);
/* allow independent dynamic disabling of cleancache and frontswap */
static int use_cleancache = 1;
static int __init no_cleancache(char *s)
{
use_cleancache = 0;
return 1;
}
__setup("nocleancache", no_cleancache);
static int use_frontswap = 1;
static int __init no_frontswap(char *s)
{
use_frontswap = 0;
return 1;
}
__setup("nofrontswap", no_frontswap);
static int __init zcache_init(void)
{
int ret = 0;
#ifdef CONFIG_SYSFS
ret = sysfs_create_group(mm_kobj, &zcache_attr_group);
if (ret) {
pr_err("zcache: can't create sysfs\n");
goto out;
}
#endif /* CONFIG_SYSFS */
#if defined(CONFIG_CLEANCACHE) || defined(CONFIG_FRONTSWAP)
if (zcache_enabled) {
unsigned int cpu;
tmem_register_hostops(&zcache_hostops);
tmem_register_pamops(&zcache_pamops);
ret = register_cpu_notifier(&zcache_cpu_notifier_block);
if (ret) {
pr_err("zcache: can't register cpu notifier\n");
goto out;
}
for_each_online_cpu(cpu) {
void *pcpu = (void *)(long)cpu;
zcache_cpu_notifier(&zcache_cpu_notifier_block,
CPU_UP_PREPARE, pcpu);
}
}
zcache_objnode_cache = kmem_cache_create("zcache_objnode",
sizeof(struct tmem_objnode), 0, 0, NULL);
zcache_obj_cache = kmem_cache_create("zcache_obj",
sizeof(struct tmem_obj), 0, 0, NULL);
ret = zcache_new_client(LOCAL_CLIENT);
if (ret) {
pr_err("zcache: can't create client\n");
goto out;
}
#endif
#ifdef CONFIG_CLEANCACHE
if (zcache_enabled && use_cleancache) {
struct cleancache_ops old_ops;
zbud_init();
register_shrinker(&zcache_shrinker);
old_ops = zcache_cleancache_register_ops();
pr_info("zcache: cleancache enabled using kernel "
"transcendent memory and compression buddies\n");
if (old_ops.init_fs != NULL)
pr_warning("zcache: cleancache_ops overridden");
}
#endif
#ifdef CONFIG_FRONTSWAP
if (zcache_enabled && use_frontswap) {
struct frontswap_ops old_ops;
old_ops = zcache_frontswap_register_ops();
pr_info("zcache: frontswap enabled using kernel "
"transcendent memory and xvmalloc\n");
if (old_ops.init != NULL)
pr_warning("zcache: frontswap_ops overridden");
}
#endif
out:
return ret;
}
module_init(zcache_init)