The patch titled
Subject: zram: share dictionaries between per-CPU contexts
has been added to the -mm mm-unstable branch. Its filename is
zram-share-dictionaries-between-per-cpu-contexts.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-share-dictionaries-between-per-cpu-contexts.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: share dictionaries between per-CPU contexts
Date: Wed, 15 May 2024 16:12:54 +0900
zstd's CDict and DDict are accessed read-only during compression and
decompression, so instead of allocation per-context dictionaries we can
create just one CDict and DDict in init_config() and make per-CPU contexts
use them. This saves quite a lot of memory: on my system CDict requires
408128 bytes and DDict requires 27352 bytes.
Link: https://lkml.kernel.org/r/20240515071645.1788128-18-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nick Terrell <terrelln@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/backend_zstd.c | 108 ++++++++++++++++++----------
1 file changed, 72 insertions(+), 36 deletions(-)
--- a/drivers/block/zram/backend_zstd.c~zram-share-dictionaries-between-per-cpu-contexts
+++ a/drivers/block/zram/backend_zstd.c
@@ -7,14 +7,18 @@
#include "backend_zstd.h"
+struct zstd_ctx_data {
+ zstd_custom_mem ctx_mem;
+ zstd_cdict *cdict;
+ zstd_ddict *ddict;
+};
+
struct zstd_ctx {
zstd_cctx *cctx;
zstd_dctx *dctx;
void *cctx_mem;
void *dctx_mem;
- zstd_custom_mem ctx_mem;
- zstd_cdict *cdict;
- zstd_ddict *ddict;
+ struct zstd_ctx_data *ctx_data;
s32 level;
};
@@ -38,32 +42,81 @@ static void zstd_ctx_free(void *opaque,
static int zstd_init_config(struct zcomp_config *config)
{
+ struct zstd_ctx_data *ctx_data = config->private;
+ zstd_compression_parameters params;
+
+ /* Already initialized */
+ if (ctx_data)
+ return 0;
+
if (config->level == ZCOMP_CONFIG_NO_LEVEL)
config->level = zstd_default_clevel();
+ if (config->dict_sz == 0)
+ return 0;
+
+ ctx_data = kzalloc(sizeof(*ctx_data), GFP_KERNEL);
+ if (!ctx_data)
+ return -ENOMEM;
+
+ ctx_data->ctx_mem.customAlloc = zstd_ctx_alloc;
+ ctx_data->ctx_mem.customFree = zstd_ctx_free;
+
+ params = zstd_get_cparams(config->level, PAGE_SIZE, config->dict_sz);
+
+ ctx_data->cdict = zstd_create_cdict_advanced(config->dict,
+ config->dict_sz,
+ ZSTD_dlm_byRef,
+ ZSTD_dct_auto,
+ params,
+ ctx_data->ctx_mem);
+ if (!ctx_data->cdict)
+ goto error;
+
+ ctx_data->ddict = zstd_create_ddict_advanced(config->dict,
+ config->dict_sz,
+ ZSTD_dlm_byRef,
+ ZSTD_dct_auto,
+ ctx_data->ctx_mem);
+ if (!ctx_data->ddict)
+ goto error;
+
+ config->private = ctx_data;
return 0;
+
+error:
+ zstd_free_cdict(ctx_data->cdict);
+ zstd_free_ddict(ctx_data->ddict);
+ kfree(ctx_data);
+ return -EINVAL;
}
static void zstd_release_config(struct zcomp_config *config)
{
+ struct zstd_ctx_data *ctx_data = config->private;
+
+ if (!ctx_data)
+ return;
+
+ config->private = NULL;
+ zstd_free_cdict(ctx_data->cdict);
+ zstd_free_ddict(ctx_data->ddict);
+ kfree(ctx_data);
}
static void zstd_destroy(void *ctx)
{
struct zstd_ctx *zctx = ctx;
+ /* Don't free zctx->ctx_data, it's done in release_config() */
if (zctx->cctx_mem)
vfree(zctx->cctx_mem);
else
zstd_free_cctx(zctx->cctx);
-
if (zctx->dctx_mem)
vfree(zctx->dctx_mem);
else
zstd_free_dctx(zctx->dctx);
-
- zstd_free_cdict(zctx->cdict);
- zstd_free_ddict(zctx->ddict);
kfree(zctx);
}
@@ -75,9 +128,8 @@ static void *zstd_create(struct zcomp_co
if (!ctx)
return NULL;
+ ctx->ctx_data = config->private;
ctx->level = config->level;
- ctx->ctx_mem.customAlloc = zstd_ctx_alloc;
- ctx->ctx_mem.customFree = zstd_ctx_free;
if (config->dict_sz == 0) {
zstd_parameters params;
@@ -102,35 +154,15 @@ static void *zstd_create(struct zcomp_co
if (!ctx->dctx)
goto error;
} else {
- zstd_compression_parameters params;
+ struct zstd_ctx_data *ctx_data = ctx->ctx_data;
- ctx->cctx = zstd_create_cctx_advanced(ctx->ctx_mem);
+ ctx->cctx = zstd_create_cctx_advanced(ctx_data->ctx_mem);
if (!ctx->cctx)
goto error;
- ctx->dctx = zstd_create_dctx_advanced(ctx->ctx_mem);
+ ctx->dctx = zstd_create_dctx_advanced(ctx_data->ctx_mem);
if (!ctx->dctx)
goto error;
-
- params = zstd_get_cparams(ctx->level, PAGE_SIZE,
- config->dict_sz);
-
- ctx->cdict = zstd_create_cdict_advanced(config->dict,
- config->dict_sz,
- ZSTD_dlm_byRef,
- ZSTD_dct_auto,
- params,
- ctx->ctx_mem);
- if (!ctx->cdict)
- goto error;
-
- ctx->ddict = zstd_create_ddict_advanced(config->dict,
- config->dict_sz,
- ZSTD_dlm_byRef,
- ZSTD_dct_auto,
- ctx->ctx_mem);
- if (!ctx->ddict)
- goto error;
}
return ctx;
@@ -144,15 +176,17 @@ static int zstd_compress(void *ctx, cons
unsigned char *dst, size_t *dst_len)
{
struct zstd_ctx *zctx = ctx;
+ struct zstd_ctx_data *ctx_data = zctx->ctx_data;
const zstd_parameters params = zstd_get_params(zctx->level, PAGE_SIZE);
size_t ret;
- if (!zctx->cdict)
+ if (!ctx_data)
ret = zstd_compress_cctx(zctx->cctx, dst, *dst_len,
src, PAGE_SIZE, ¶ms);
else
ret = zstd_compress_using_cdict(zctx->cctx, dst, *dst_len,
- src, PAGE_SIZE, zctx->cdict);
+ src, PAGE_SIZE,
+ ctx_data->cdict);
if (zstd_is_error(ret))
return -EINVAL;
*dst_len = ret;
@@ -163,14 +197,16 @@ static int zstd_decompress(void *ctx, co
unsigned char *dst)
{
struct zstd_ctx *zctx = ctx;
+ struct zstd_ctx_data *ctx_data = zctx->ctx_data;
size_t ret;
- if (!zctx->ddict)
+ if (!ctx_data)
ret = zstd_decompress_dctx(zctx->dctx, dst, PAGE_SIZE,
src, src_len);
else
ret = zstd_decompress_using_ddict(zctx->dctx, dst, PAGE_SIZE,
- src, src_len, zctx->ddict);
+ src, src_len,
+ ctx_data->ddict);
if (zstd_is_error(ret))
return -EINVAL;
return 0;
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zram-move-from-crypto-api-to-custom-comp-backends-api.patch
zram-add-lzo-and-lzorle-compression-backends-support.patch
zram-add-lz4-compression-backend-support.patch
zram-add-lz4hc-compression-backend-support.patch
zram-add-zstd-compression-backend-support.patch
zram-pass-estimated-src-size-hint-to-zstd.patch
zram-add-zlib-compression-backend-support.patch
zram-add-842-compression-backend-support.patch
zram-check-that-backends-array-has-at-least-one-backend.patch
zram-introduce-zcomp_config-structure.patch
zram-extend-comp_algorithm-attr-write-handling.patch
zram-support-compression-level-comp-config.patch
zram-add-support-for-dict-comp-config.patch
lib-zstd-export-api-needed-for-dictionary-support.patch
zram-add-dictionary-support-to-zstd-backend.patch
zram-add-config-init-release-backend-callbacks.patch
zram-share-dictionaries-between-per-cpu-contexts.patch
zram-add-dictionary-support-to-lz4.patch
lib-lz4hc-export-lz4_resetstreamhc-symbol.patch
zram-add-dictionary-support-to-lz4hc.patch
documentation-zram-add-documentation-for-algorithm-parameters.patch
