Hi Chao,
On 2025/7/10 15:36, Chao Yu wrote:
This patch supports to readahead more blocks in erofs_readdir(),
it can enhance performance in large direcotry.
readdir test in a large directory which contains 12000 sub-files.
files_per_second
Before: 926385.54
After: 2380435.562
Signed-off-by: Chao Yu <c...@kernel.org>
---
fs/erofs/dir.c | 8 ++++++++
fs/erofs/internal.h | 3 +++
2 files changed, 11 insertions(+)
diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c
index cff61c5a172b..04113851fc0f 100644
--- a/fs/erofs/dir.c
+++ b/fs/erofs/dir.c
@@ -47,8 +47,10 @@ static int erofs_readdir(struct file *f, struct dir_context
*ctx)
struct inode *dir = file_inode(f);
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
struct super_block *sb = dir->i_sb;
+ struct file_ra_state *ra = &f->f_ra;
unsigned long bsz = sb->s_blocksize;
unsigned int ofs = erofs_blkoff(sb, ctx->pos);
+ unsigned long nr_pages = DIV_ROUND_UP_POW2(dir->i_size, PAGE_SIZE);
int err = 0;
bool initial = true;
@@ -65,6 +67,12 @@ static int erofs_readdir(struct file *f, struct dir_context *ctx)
}
cond_resched();
+ /* readahead blocks to enhance performance in large directory */
+ if (nr_pages - dbstart > 1 && !ra_has_index(ra, dbstart))
+ page_cache_sync_readahead(dir->i_mapping, ra, f,
+ dbstart, min(nr_pages - dbstart,
+ (pgoff_t)MAX_DIR_RA_PAGES));
+
de = erofs_bread(&buf, dbstart, true);
if (IS_ERR(de)) {
erofs_err(sb, "failed to readdir of logical block %llu of
nid %llu",
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index a32c03a80c70..ef9d1ee8c688 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -238,6 +238,9 @@ EROFS_FEATURE_FUNCS(xattr_filter, compat,
COMPAT_XATTR_FILTER)
#define EROFS_I_BL_XATTR_BIT (BITS_PER_LONG - 1)
#define EROFS_I_BL_Z_BIT (BITS_PER_LONG - 2)
+/* maximum readahead pages of directory */
+#define MAX_DIR_RA_PAGES 4
Could we set it as a per-sb sysfs configuration for users to config?
Thanks,
Gao Xiang
