[f2fs-dev] [PATCH 1/2] f2fs: use vmalloc instead of kvmalloc in .init_{, de}compress_ctx

[Chao Yu via Linux-f2fs-devel]

.init_{,de}compress_ctx uses kvmalloc() to alloc memory, it will try
to allocate physically continuous page first, it may cause more memory
allocation pressure, let's use vmalloc instead to mitigate it.

[Test]
cd /data/local/tmp
touch file
f2fs_io setflags compression file
f2fs_io getflags file
for i in $(seq 1 10); do sync; echo 3 > /proc/sys/vm/drop_caches;\
time f2fs_io write 512 0 4096 zero osync file; truncate -s 0 file;\
done

[Result]
Before          After           Delta
21.243          21.694          -2.12%

For compression, we recommend to use ioctl to compress file data in
background for workaround.

For decompression, only zstd will be affected.

Signed-off-by: Chao Yu <c...@kernel.org>
---
 fs/f2fs/compress.c | 23 ++++++++++-------------
 fs/f2fs/f2fs.h     |  5 +++++
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 1e62fdffda07..37d18e2a3327 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -180,8 +180,7 @@ void f2fs_compress_ctx_add_page(struct compress_ctx *cc, 
struct folio *folio)
 #ifdef CONFIG_F2FS_FS_LZO
 static int lzo_init_compress_ctx(struct compress_ctx *cc)
 {
-       cc->private = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
-                               LZO1X_MEM_COMPRESS, GFP_NOFS);
+       cc->private = f2fs_vmalloc(LZO1X_MEM_COMPRESS);
        if (!cc->private)
                return -ENOMEM;
 
@@ -191,7 +190,7 @@ static int lzo_init_compress_ctx(struct compress_ctx *cc)
 
 static void lzo_destroy_compress_ctx(struct compress_ctx *cc)
 {
-       kvfree(cc->private);
+       vfree(cc->private);
        cc->private = NULL;
 }
 
@@ -248,7 +247,7 @@ static int lz4_init_compress_ctx(struct compress_ctx *cc)
                size = LZ4HC_MEM_COMPRESS;
 #endif
 
-       cc->private = f2fs_kvmalloc(F2FS_I_SB(cc->inode), size, GFP_NOFS);
+       cc->private = f2fs_vmalloc(size);
        if (!cc->private)
                return -ENOMEM;
 
@@ -263,7 +262,7 @@ static int lz4_init_compress_ctx(struct compress_ctx *cc)
 
 static void lz4_destroy_compress_ctx(struct compress_ctx *cc)
 {
-       kvfree(cc->private);
+       vfree(cc->private);
        cc->private = NULL;
 }
 
@@ -344,8 +343,7 @@ static int zstd_init_compress_ctx(struct compress_ctx *cc)
        params = zstd_get_params(level, cc->rlen);
        workspace_size = zstd_cstream_workspace_bound(&params.cParams);
 
-       workspace = f2fs_kvmalloc(F2FS_I_SB(cc->inode),
-                                       workspace_size, GFP_NOFS);
+       workspace = f2fs_vmalloc(workspace_size);
        if (!workspace)
                return -ENOMEM;
 
@@ -353,7 +351,7 @@ static int zstd_init_compress_ctx(struct compress_ctx *cc)
        if (!stream) {
                f2fs_err_ratelimited(F2FS_I_SB(cc->inode),
                                "%s zstd_init_cstream failed", __func__);
-               kvfree(workspace);
+               vfree(workspace);
                return -EIO;
        }
 
@@ -366,7 +364,7 @@ static int zstd_init_compress_ctx(struct compress_ctx *cc)
 
 static void zstd_destroy_compress_ctx(struct compress_ctx *cc)
 {
-       kvfree(cc->private);
+       vfree(cc->private);
        cc->private = NULL;
        cc->private2 = NULL;
 }
@@ -425,8 +423,7 @@ static int zstd_init_decompress_ctx(struct 
decompress_io_ctx *dic)
 
        workspace_size = zstd_dstream_workspace_bound(max_window_size);
 
-       workspace = f2fs_kvmalloc(F2FS_I_SB(dic->inode),
-                                       workspace_size, GFP_NOFS);
+       workspace = f2fs_vmalloc(workspace_size);
        if (!workspace)
                return -ENOMEM;
 
@@ -434,7 +431,7 @@ static int zstd_init_decompress_ctx(struct 
decompress_io_ctx *dic)
        if (!stream) {
                f2fs_err_ratelimited(F2FS_I_SB(dic->inode),
                                "%s zstd_init_dstream failed", __func__);
-               kvfree(workspace);
+               vfree(workspace);
                return -EIO;
        }
 
@@ -446,7 +443,7 @@ static int zstd_init_decompress_ctx(struct 
decompress_io_ctx *dic)
 
 static void zstd_destroy_decompress_ctx(struct decompress_io_ctx *dic)
 {
-       kvfree(dic->private);
+       vfree(dic->private);
        dic->private = NULL;
        dic->private2 = NULL;
 }
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 9432fd15766a..6e9615b5cdc3 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3540,6 +3540,11 @@ static inline void *f2fs_kvzalloc(struct f2fs_sb_info 
*sbi,
        return f2fs_kvmalloc(sbi, size, flags | __GFP_ZERO);
 }
 
+static inline void *f2fs_vmalloc(size_t size)
+{
+       return vmalloc(size);
+}
+
 static inline int get_extra_isize(struct inode *inode)
 {
        return F2FS_I(inode)->i_extra_isize / sizeof(__le32);
-- 
2.49.0



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