Commit 30048cda authored by Huang Jianan's avatar Huang Jianan Committed by Gao Xiang
Browse files

erofs: use sync decompression for atomic contexts only 

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.

Link: https://lore.kernel.org/r/20210317035448.13921-3-huangjianan@oppo.com


Reviewed-by: default avatarGao Xiang <hsiangkao@redhat.com>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarHuang Jianan <huangjianan@oppo.com>
Signed-off-by: default avatarGuo Weichao <guoweichao@oppo.com>
Signed-off-by: default avatarGao Xiang <hsiangkao@redhat.com>
parent 648f2de0

fs/erofs/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -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;

fs/erofs/super.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

fs/erofs/zdata.c

+6 −2
Original line number Diff line number Diff line
@@ -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);