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authorBarry Song <song.bao.hua@hisilicon.com>2020-12-14 19:14:18 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-15 12:13:46 -0800
commit1ec3b5fe6eec782f4e5e0a80e4ce1909ffd5d161 (patch)
tree00926fd21696c2b9101ef6a2e1e91c1d3823653d
parent42a44704367cd18d069c9855cb84090ff90ecd86 (diff)
mm/zswap: move to use crypto_acomp API for hardware acceleration
Right now, all new ZIP drivers are adapted to crypto_acomp APIs rather than legacy crypto_comp APIs. Tradiontal ZIP drivers like lz4,lzo etc have been also wrapped into acomp via scomp backend. But zswap.c is still using the old APIs. That means zswap won't be able to work on any new ZIP drivers in kernel. This patch moves to use cryto_acomp APIs to fix the disconnected bridge between new ZIP drivers and zswap. It is probably the first real user to use acomp but perhaps not a good example to demonstrate how multiple acomp requests can be executed in parallel in one acomp instance. frontswap is doing page load and store page by page synchronously. swap_writepage() depends on the completion of frontswap_store() to decide if it should call __swap_writepage() to swap to disk. However this patch creates multiple acomp instances, so multiple threads running on multiple different cpus can actually do (de)compression parallelly, leveraging the power of multiple ZIP hardware queues. This is also consistent with frontswap's page management model. The old zswap code uses atomic context and avoids the race conditions while shared resources like zswap_dstmem are accessed. Here since acomp can sleep, per-cpu mutex is used to replace preemption-disable. While it is possible to make mm/page_io.c and mm/frontswap.c support async (de)compression in some way, the entire design requires careful thinking and performance evaluation. For the first step, the base with fixed connection between ZIP drivers and zswap should be built. Link: https://lkml.kernel.org/r/20201107065332.26992-1-song.bao.hua@hisilicon.com Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Acked-by: Vitaly Wool <vitalywool@gmail.com> Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: David S. Miller <davem@davemloft.net> Cc: Mahipal Challa <mahipalreddy2006@gmail.com> Cc: Seth Jennings <sjenning@redhat.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Zhou Wang <wangzhou1@hisilicon.com> Cc: Colin Ian King <colin.king@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/zswap.c183
1 files changed, 137 insertions, 46 deletions
diff --git a/mm/zswap.c b/mm/zswap.c
index 55a2f72557a8..182f6ad5aa69 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -24,8 +24,10 @@
#include <linux/rbtree.h>
#include <linux/swap.h>
#include <linux/crypto.h>
+#include <linux/scatterlist.h>
#include <linux/mempool.h>
#include <linux/zpool.h>
+#include <crypto/acompress.h>
#include <linux/mm_types.h>
#include <linux/page-flags.h>
@@ -127,9 +129,17 @@ module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
* data structures
**********************************/
+struct crypto_acomp_ctx {
+ struct crypto_acomp *acomp;
+ struct acomp_req *req;
+ struct crypto_wait wait;
+ u8 *dstmem;
+ struct mutex *mutex;
+};
+
struct zswap_pool {
struct zpool *zpool;
- struct crypto_comp * __percpu *tfm;
+ struct crypto_acomp_ctx __percpu *acomp_ctx;
struct kref kref;
struct list_head list;
struct work_struct release_work;
@@ -388,23 +398,43 @@ static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
* per-cpu code
**********************************/
static DEFINE_PER_CPU(u8 *, zswap_dstmem);
+/*
+ * If users dynamically change the zpool type and compressor at runtime, i.e.
+ * zswap is running, zswap can have more than one zpool on one cpu, but they
+ * are sharing dtsmem. So we need this mutex to be per-cpu.
+ */
+static DEFINE_PER_CPU(struct mutex *, zswap_mutex);
static int zswap_dstmem_prepare(unsigned int cpu)
{
+ struct mutex *mutex;
u8 *dst;
dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
if (!dst)
return -ENOMEM;
+ mutex = kmalloc_node(sizeof(*mutex), GFP_KERNEL, cpu_to_node(cpu));
+ if (!mutex) {
+ kfree(dst);
+ return -ENOMEM;
+ }
+
+ mutex_init(mutex);
per_cpu(zswap_dstmem, cpu) = dst;
+ per_cpu(zswap_mutex, cpu) = mutex;
return 0;
}
static int zswap_dstmem_dead(unsigned int cpu)
{
+ struct mutex *mutex;
u8 *dst;
+ mutex = per_cpu(zswap_mutex, cpu);
+ kfree(mutex);
+ per_cpu(zswap_mutex, cpu) = NULL;
+
dst = per_cpu(zswap_dstmem, cpu);
kfree(dst);
per_cpu(zswap_dstmem, cpu) = NULL;
@@ -415,30 +445,54 @@ static int zswap_dstmem_dead(unsigned int cpu)
static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
- struct crypto_comp *tfm;
-
- if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
- return 0;
+ struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
+ struct crypto_acomp *acomp;
+ struct acomp_req *req;
+
+ acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
+ if (IS_ERR(acomp)) {
+ pr_err("could not alloc crypto acomp %s : %ld\n",
+ pool->tfm_name, PTR_ERR(acomp));
+ return PTR_ERR(acomp);
+ }
+ acomp_ctx->acomp = acomp;
- tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
- if (IS_ERR(tfm)) {
- pr_err("could not alloc crypto comp %s : %ld\n",
- pool->tfm_name, PTR_ERR(tfm));
+ req = acomp_request_alloc(acomp_ctx->acomp);
+ if (!req) {
+ pr_err("could not alloc crypto acomp_request %s\n",
+ pool->tfm_name);
+ crypto_free_acomp(acomp_ctx->acomp);
return -ENOMEM;
}
- *per_cpu_ptr(pool->tfm, cpu) = tfm;
+ acomp_ctx->req = req;
+
+ crypto_init_wait(&acomp_ctx->wait);
+ /*
+ * if the backend of acomp is async zip, crypto_req_done() will wakeup
+ * crypto_wait_req(); if the backend of acomp is scomp, the callback
+ * won't be called, crypto_wait_req() will return without blocking.
+ */
+ acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+ crypto_req_done, &acomp_ctx->wait);
+
+ acomp_ctx->mutex = per_cpu(zswap_mutex, cpu);
+ acomp_ctx->dstmem = per_cpu(zswap_dstmem, cpu);
+
return 0;
}
static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
{
struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
- struct crypto_comp *tfm;
+ struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
+
+ if (!IS_ERR_OR_NULL(acomp_ctx)) {
+ if (!IS_ERR_OR_NULL(acomp_ctx->req))
+ acomp_request_free(acomp_ctx->req);
+ if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
+ crypto_free_acomp(acomp_ctx->acomp);
+ }
- tfm = *per_cpu_ptr(pool->tfm, cpu);
- if (!IS_ERR_OR_NULL(tfm))
- crypto_free_comp(tfm);
- *per_cpu_ptr(pool->tfm, cpu) = NULL;
return 0;
}
@@ -561,8 +615,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
- pool->tfm = alloc_percpu(struct crypto_comp *);
- if (!pool->tfm) {
+
+ pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx);
+ if (!pool->acomp_ctx) {
pr_err("percpu alloc failed\n");
goto error;
}
@@ -585,7 +640,8 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
return pool;
error:
- free_percpu(pool->tfm);
+ if (pool->acomp_ctx)
+ free_percpu(pool->acomp_ctx);
if (pool->zpool)
zpool_destroy_pool(pool->zpool);
kfree(pool);
@@ -596,14 +652,14 @@ static __init struct zswap_pool *__zswap_pool_create_fallback(void)
{
bool has_comp, has_zpool;
- has_comp = crypto_has_comp(zswap_compressor, 0, 0);
+ has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
if (!has_comp && strcmp(zswap_compressor,
CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
pr_err("compressor %s not available, using default %s\n",
zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
param_free_charp(&zswap_compressor);
zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
- has_comp = crypto_has_comp(zswap_compressor, 0, 0);
+ has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
}
if (!has_comp) {
pr_err("default compressor %s not available\n",
@@ -639,7 +695,7 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
zswap_pool_debug("destroying", pool);
cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
- free_percpu(pool->tfm);
+ free_percpu(pool->acomp_ctx);
zpool_destroy_pool(pool->zpool);
kfree(pool);
}
@@ -723,7 +779,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
}
type = s;
} else if (!compressor) {
- if (!crypto_has_comp(s, 0, 0)) {
+ if (!crypto_has_acomp(s, 0, 0)) {
pr_err("compressor %s not available\n", s);
return -ENOENT;
}
@@ -774,7 +830,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
* failed, maybe both compressor and zpool params were bad.
* Allow changing this param, so pool creation will succeed
* when the other param is changed. We already verified this
- * param is ok in the zpool_has_pool() or crypto_has_comp()
+ * param is ok in the zpool_has_pool() or crypto_has_acomp()
* checks above.
*/
ret = param_set_charp(s, kp);
@@ -876,8 +932,10 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
pgoff_t offset;
struct zswap_entry *entry;
struct page *page;
- struct crypto_comp *tfm;
- u8 *src, *dst;
+ struct scatterlist input, output;
+ struct crypto_acomp_ctx *acomp_ctx;
+
+ u8 *src;
unsigned int dlen;
int ret;
struct writeback_control wbc = {
@@ -916,14 +974,20 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
case ZSWAP_SWAPCACHE_NEW: /* page is locked */
/* decompress */
+ acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
+
dlen = PAGE_SIZE;
src = (u8 *)zhdr + sizeof(struct zswap_header);
- dst = kmap_atomic(page);
- tfm = *get_cpu_ptr(entry->pool->tfm);
- ret = crypto_comp_decompress(tfm, src, entry->length,
- dst, &dlen);
- put_cpu_ptr(entry->pool->tfm);
- kunmap_atomic(dst);
+
+ mutex_lock(acomp_ctx->mutex);
+ sg_init_one(&input, src, entry->length);
+ sg_init_table(&output, 1);
+ sg_set_page(&output, page, PAGE_SIZE, 0);
+ acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
+ ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
+ dlen = acomp_ctx->req->dlen;
+ mutex_unlock(acomp_ctx->mutex);
+
BUG_ON(ret);
BUG_ON(dlen != PAGE_SIZE);
@@ -1004,7 +1068,8 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry, *dupentry;
- struct crypto_comp *tfm;
+ struct scatterlist input, output;
+ struct crypto_acomp_ctx *acomp_ctx;
int ret;
unsigned int hlen, dlen = PAGE_SIZE;
unsigned long handle, value;
@@ -1074,12 +1139,32 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
}
/* compress */
- dst = get_cpu_var(zswap_dstmem);
- tfm = *get_cpu_ptr(entry->pool->tfm);
- src = kmap_atomic(page);
- ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
- kunmap_atomic(src);
- put_cpu_ptr(entry->pool->tfm);
+ acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
+
+ mutex_lock(acomp_ctx->mutex);
+
+ dst = acomp_ctx->dstmem;
+ sg_init_table(&input, 1);
+ sg_set_page(&input, page, PAGE_SIZE, 0);
+
+ /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
+ sg_init_one(&output, dst, PAGE_SIZE * 2);
+ acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
+ /*
+ * it maybe looks a little bit silly that we send an asynchronous request,
+ * then wait for its completion synchronously. This makes the process look
+ * synchronous in fact.
+ * Theoretically, acomp supports users send multiple acomp requests in one
+ * acomp instance, then get those requests done simultaneously. but in this
+ * case, frontswap actually does store and load page by page, there is no
+ * existing method to send the second page before the first page is done
+ * in one thread doing frontswap.
+ * but in different threads running on different cpu, we have different
+ * acomp instance, so multiple threads can do (de)compression in parallel.
+ */
+ ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
+ dlen = acomp_ctx->req->dlen;
+
if (ret) {
ret = -EINVAL;
goto put_dstmem;
@@ -1103,7 +1188,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
memcpy(buf, &zhdr, hlen);
memcpy(buf + hlen, dst, dlen);
zpool_unmap_handle(entry->pool->zpool, handle);
- put_cpu_var(zswap_dstmem);
+ mutex_unlock(acomp_ctx->mutex);
/* populate entry */
entry->offset = offset;
@@ -1131,7 +1216,7 @@ insert_entry:
return 0;
put_dstmem:
- put_cpu_var(zswap_dstmem);
+ mutex_unlock(acomp_ctx->mutex);
zswap_pool_put(entry->pool);
freepage:
zswap_entry_cache_free(entry);
@@ -1148,7 +1233,8 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
{
struct zswap_tree *tree = zswap_trees[type];
struct zswap_entry *entry;
- struct crypto_comp *tfm;
+ struct scatterlist input, output;
+ struct crypto_acomp_ctx *acomp_ctx;
u8 *src, *dst;
unsigned int dlen;
int ret;
@@ -1175,11 +1261,16 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
if (zpool_evictable(entry->pool->zpool))
src += sizeof(struct zswap_header);
- dst = kmap_atomic(page);
- tfm = *get_cpu_ptr(entry->pool->tfm);
- ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
- put_cpu_ptr(entry->pool->tfm);
- kunmap_atomic(dst);
+
+ acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
+ mutex_lock(acomp_ctx->mutex);
+ sg_init_one(&input, src, entry->length);
+ sg_init_table(&output, 1);
+ sg_set_page(&output, page, PAGE_SIZE, 0);
+ acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
+ ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
+ mutex_unlock(acomp_ctx->mutex);
+
zpool_unmap_handle(entry->pool->zpool, entry->handle);
BUG_ON(ret);