This patch set was separated form erofs: decompress in endio if possible
since it does these things:
- combine dm-verity and erofs workqueue
- change policy of decompression in context of thread
Huang Jianan (2):
erofs: use workqueue decompression for atomic contexts only
erofs: use sync decompression for atomic contexts only
fs/erofs/internal.h | 2 ++
fs/erofs/super.c | 1 +
fs/erofs/zdata.c | 15 +++++++++++++--
3 files changed, 16 insertions(+), 2 deletions(-)
--
2.25.1
z_erofs_decompressqueue_endio may not be executed in the atomic
context, for example, when dm-verity is turned on. In this scenario,
data can be decompressed directly to get rid of additional kworker
scheduling overhead.
Signed-off-by: Huang Jianan <[email protected]>
Signed-off-by: Guo Weichao <[email protected]>
Reviewed-by: Gao Xiang <[email protected]>
---
fs/erofs/zdata.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 6cb356c4217b..cf2d28582c14 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -706,6 +706,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
goto out;
}
+static void z_erofs_decompressqueue_work(struct work_struct *work);
static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
bool sync, int bios)
{
@@ -720,8 +721,14 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
return;
}
- if (!atomic_add_return(bios, &io->pending_bios))
+ if (atomic_add_return(bios, &io->pending_bios))
+ return;
+ /* Use workqueue decompression for atomic contexts only */
+ if (in_atomic() || irqs_disabled()) {
queue_work(z_erofs_workqueue, &io->u.work);
+ return;
+ }
+ z_erofs_decompressqueue_work(&io->u.work);
}
static bool z_erofs_page_is_invalidated(struct page *page)
--
2.25.1
Sync decompression was introduced to get rid of additional kworker
scheduling overhead. But there is no such overhead in non-atomic
contexts. Therefore, it should be better to turn off sync decompression
to avoid the current thread waiting in z_erofs_runqueue.
Signed-off-by: Huang Jianan <[email protected]>
Signed-off-by: Guo Weichao <[email protected]>
Reviewed-by: Gao Xiang <[email protected]>
---
fs/erofs/internal.h | 2 ++
fs/erofs/super.c | 1 +
fs/erofs/zdata.c | 8 ++++++--
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 67a7ec945686..fbc4040715be 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -50,6 +50,8 @@ struct erofs_fs_context {
#ifdef CONFIG_EROFS_FS_ZIP
/* current strategy of how to use managed cache */
unsigned char cache_strategy;
+ /* strategy of sync decompression (false - auto, true - force on) */
+ bool readahead_sync_decompress;
/* threshold for decompression synchronously */
unsigned int max_sync_decompress_pages;
diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index d5a6b9b888a5..0445d09b6331 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -200,6 +200,7 @@ static void erofs_default_options(struct erofs_fs_context *ctx)
#ifdef CONFIG_EROFS_FS_ZIP
ctx->cache_strategy = EROFS_ZIP_CACHE_READAROUND;
ctx->max_sync_decompress_pages = 3;
+ ctx->readahead_sync_decompress = false;
#endif
#ifdef CONFIG_EROFS_FS_XATTR
set_opt(ctx, XATTR_USER);
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index cf2d28582c14..25a0c4890d0a 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -710,6 +710,8 @@ static void z_erofs_decompressqueue_work(struct work_struct *work);
static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
bool sync, int bios)
{
+ struct erofs_sb_info *const sbi = EROFS_SB(io->sb);
+
/* wake up the caller thread for sync decompression */
if (sync) {
unsigned long flags;
@@ -723,9 +725,10 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
if (atomic_add_return(bios, &io->pending_bios))
return;
- /* Use workqueue decompression for atomic contexts only */
+ /* Use workqueue and sync decompression for atomic contexts only */
if (in_atomic() || irqs_disabled()) {
queue_work(z_erofs_workqueue, &io->u.work);
+ sbi->ctx.readahead_sync_decompress = true;
return;
}
z_erofs_decompressqueue_work(&io->u.work);
@@ -1340,7 +1343,8 @@ static void z_erofs_readahead(struct readahead_control *rac)
struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
unsigned int nr_pages = readahead_count(rac);
- bool sync = (nr_pages <= sbi->ctx.max_sync_decompress_pages);
+ bool sync = (sbi->ctx.readahead_sync_decompress &&
+ nr_pages <= sbi->ctx.max_sync_decompress_pages);
struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
struct page *page, *head = NULL;
LIST_HEAD(pagepool);
--
2.25.1
On 2021/3/17 11:54, Huang Jianan via Linux-erofs wrote:
> z_erofs_decompressqueue_endio may not be executed in the atomic
> context, for example, when dm-verity is turned on. In this scenario,
> data can be decompressed directly to get rid of additional kworker
> scheduling overhead.
>
> Signed-off-by: Huang Jianan <[email protected]>
> Signed-off-by: Guo Weichao <[email protected]>
> Reviewed-by: Gao Xiang <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Thanks,
On 2021/3/17 11:54, Huang Jianan via Linux-erofs wrote:
> Sync decompression was introduced to get rid of additional kworker
> scheduling overhead. But there is no such overhead in non-atomic
> contexts. Therefore, it should be better to turn off sync decompression
> to avoid the current thread waiting in z_erofs_runqueue.
>
> Signed-off-by: Huang Jianan <[email protected]>
> Signed-off-by: Guo Weichao <[email protected]>
> Reviewed-by: Gao Xiang <[email protected]>
Reviewed-by: Chao Yu <[email protected]>
Thanks,