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Message-ID: <20240712051850.484318-23-senozhatsky@chromium.org>
Date: Fri, 12 Jul 2024 14:18:33 +0900
From: Sergey Senozhatsky <senozhatsky@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
Minchan Kim <minchan@...nel.org>
Cc: linux-kernel@...r.kernel.org,
Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH v6 22/23] zram: add dictionary support to zstd backend
This adds support for pre-trained zstd dictionaries [1]
Dictionary is setup in params once (per-comp) and loaded
to Cctx and Dctx by reference, so we don't allocate extra
memory.
TEST
====
*** zstd
/sys/block/zram0/mm_stat
1750654976 504565092 514203648 0 514203648 1 0 34204 34204
*** zstd dict=/home/ss/zstd-dict-amd64
/sys/block/zram0/mm_stat
1750638592 465851259 475373568 0 475373568 1 0 34185 34185
*** zstd level=8 dict=/home/ss/zstd-dict-amd64
/sys/block/zram0/mm_stat
1750642688 430765171 439955456 0 439955456 1 0 34185 34185
[1] https://github.com/facebook/zstd/blob/dev/programs/zstd.1.md#dictionary-builder
Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
drivers/block/zram/backend_zstd.c | 150 ++++++++++++++++++++++++------
1 file changed, 124 insertions(+), 26 deletions(-)
diff --git a/drivers/block/zram/backend_zstd.c b/drivers/block/zram/backend_zstd.c
index 5b33daf4f645..1184c0036f44 100644
--- a/drivers/block/zram/backend_zstd.c
+++ b/drivers/block/zram/backend_zstd.c
@@ -15,29 +15,87 @@ struct zstd_ctx {
};
struct zstd_params {
+ zstd_custom_mem custom_mem;
+ zstd_cdict *cdict;
+ zstd_ddict *ddict;
zstd_parameters cprm;
};
+/*
+ * For C/D dictionaries we need to provide zstd with zstd_custom_mem,
+ * which zstd uses internally to allocate/free memory when needed.
+ *
+ * This means that allocator.customAlloc() can be called from zcomp_compress()
+ * under local-lock (per-CPU compression stream), in which case we must use
+ * GFP_ATOMIC.
+ *
+ * Another complication here is that we can be configured as a swap device.
+ */
+static void *zstd_custom_alloc(void *opaque, size_t size)
+{
+ if (!preemptible())
+ return kvzalloc(size, GFP_ATOMIC);
+
+ return kvzalloc(size, __GFP_KSWAPD_RECLAIM | __GFP_NOWARN);
+}
+
+static void zstd_custom_free(void *opaque, void *address)
+{
+ kvfree(address);
+}
+
static void zstd_release_params(struct zcomp_params *params)
{
- kfree(params->drv_data);
+ struct zstd_params *zp = params->drv_data;
+
+ params->drv_data = NULL;
+ if (!zp)
+ return;
+
+ zstd_free_cdict(zp->cdict);
+ zstd_free_ddict(zp->ddict);
+ kfree(zp);
}
static int zstd_setup_params(struct zcomp_params *params)
{
+ zstd_compression_parameters prm;
struct zstd_params *zp;
zp = kzalloc(sizeof(*zp), GFP_KERNEL);
if (!zp)
return -ENOMEM;
+ params->drv_data = zp;
if (params->level == ZCOMP_PARAM_NO_LEVEL)
params->level = zstd_default_clevel();
zp->cprm = zstd_get_params(params->level, PAGE_SIZE);
- params->drv_data = zp;
+
+ zp->custom_mem.customAlloc = zstd_custom_alloc;
+ zp->custom_mem.customFree = zstd_custom_free;
+
+ prm = zstd_get_cparams(params->level, PAGE_SIZE,
+ params->dict_sz);
+
+ zp->cdict = zstd_create_cdict_byreference(params->dict,
+ params->dict_sz,
+ prm,
+ zp->custom_mem);
+ if (!zp->cdict)
+ goto error;
+
+ zp->ddict = zstd_create_ddict_byreference(params->dict,
+ params->dict_sz,
+ zp->custom_mem);
+ if (!zp->ddict)
+ goto error;
return 0;
+
+error:
+ zstd_release_params(params);
+ return -EINVAL;
}
static void zstd_destroy(struct zcomp_ctx *ctx)
@@ -47,8 +105,23 @@ static void zstd_destroy(struct zcomp_ctx *ctx)
if (!zctx)
return;
- vfree(zctx->cctx_mem);
- vfree(zctx->dctx_mem);
+ /*
+ * If ->cctx_mem and ->dctx_mem were allocated then we didn't use
+ * C/D dictionary and ->cctx / ->dctx were "embedded" into these
+ * buffers.
+ *
+ * If otherwise then we need to explicitly release ->cctx / ->dctx.
+ */
+ 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);
+
kfree(zctx);
}
@@ -63,28 +136,41 @@ static int zstd_create(struct zcomp_params *params, struct zcomp_ctx *ctx)
return -ENOMEM;
ctx->context = zctx;
- prm = zstd_get_params(params->level, PAGE_SIZE);
- sz = zstd_cctx_workspace_bound(&prm.cParams);
- zctx->cctx_mem = vzalloc(sz);
- if (!zctx->cctx_mem)
- goto error;
-
- zctx->cctx = zstd_init_cctx(zctx->cctx_mem, sz);
- if (!zctx->cctx)
- goto error;
-
- sz = zstd_dctx_workspace_bound();
- zctx->dctx_mem = vzalloc(sz);
- if (!zctx->dctx_mem)
- goto error;
-
- zctx->dctx = zstd_init_dctx(zctx->dctx_mem, sz);
- if (!zctx->dctx)
- goto error;
+ if (params->dict_sz == 0) {
+ prm = zstd_get_params(params->level, PAGE_SIZE);
+ sz = zstd_cctx_workspace_bound(&prm.cParams);
+ zctx->cctx_mem = vzalloc(sz);
+ if (!zctx->cctx_mem)
+ goto error;
+
+ zctx->cctx = zstd_init_cctx(zctx->cctx_mem, sz);
+ if (!zctx->cctx)
+ goto error;
+
+ sz = zstd_dctx_workspace_bound();
+ zctx->dctx_mem = vzalloc(sz);
+ if (!zctx->dctx_mem)
+ goto error;
+
+ zctx->dctx = zstd_init_dctx(zctx->dctx_mem, sz);
+ if (!zctx->dctx)
+ goto error;
+ } else {
+ struct zstd_params *zp = params->drv_data;
+
+ zctx->cctx = zstd_create_cctx_advanced(zp->custom_mem);
+ if (!zctx->cctx)
+ goto error;
+
+ zctx->dctx = zstd_create_dctx_advanced(zp->custom_mem);
+ if (!zctx->dctx)
+ goto error;
+ }
return 0;
error:
+ zstd_release_params(params);
zstd_destroy(ctx);
return -EINVAL;
}
@@ -96,8 +182,14 @@ static int zstd_compress(struct zcomp_params *params, struct zcomp_ctx *ctx,
struct zstd_ctx *zctx = ctx->context;
size_t ret;
- ret = zstd_compress_cctx(zctx->cctx, req->dst, req->dst_len,
- req->src, req->src_len, &zp->cprm);
+ if (params->dict_sz == 0)
+ ret = zstd_compress_cctx(zctx->cctx, req->dst, req->dst_len,
+ req->src, req->src_len, &zp->cprm);
+ else
+ ret = zstd_compress_using_cdict(zctx->cctx, req->dst,
+ req->dst_len, req->src,
+ req->src_len,
+ zp->cdict);
if (zstd_is_error(ret))
return -EINVAL;
req->dst_len = ret;
@@ -107,11 +199,17 @@ static int zstd_compress(struct zcomp_params *params, struct zcomp_ctx *ctx,
static int zstd_decompress(struct zcomp_params *params, struct zcomp_ctx *ctx,
struct zcomp_req *req)
{
+ struct zstd_params *zp = params->drv_data;
struct zstd_ctx *zctx = ctx->context;
size_t ret;
- ret = zstd_decompress_dctx(zctx->dctx, req->dst, req->dst_len,
- req->src, req->src_len);
+ if (params->dict_sz == 0)
+ ret = zstd_decompress_dctx(zctx->dctx, req->dst, req->dst_len,
+ req->src, req->src_len);
+ else
+ ret = zstd_decompress_using_ddict(zctx->dctx, req->dst,
+ req->dst_len, req->src,
+ req->src_len, zp->ddict);
if (zstd_is_error(ret))
return -EINVAL;
return 0;
--
2.45.2.993.g49e7a77208-goog
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