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Commit adf8d90b authored by Chao Yu's avatar Chao Yu Committed by Jaegeuk Kim
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f2fs: avoid to use slab memory in f2fs_issue_flush for efficiency 



If we use slab memory in f2fs_issue_flush(), we will face memory pressure and
latency time caused by racing of kmem_cache_{alloc,free}.

Let's alloc memory in stack instead of slab.

Signed-off-by: default avatarChao Yu <chao2.yu@samsung.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent c20e89cd

fs/f2fs/segment.c

+9 −19
Original line number Diff line number Diff line
@@ -25,7 +25,6 @@ 
#define __reverse_ffz(x) __reverse_ffs(~(x))



static struct kmem_cache *discard_entry_slab;

static struct kmem_cache *flush_cmd_slab;



/*

 * __reverse_ffs is copied from include/asm-generic/bitops/__ffs.h since
@@ -238,30 +237,28 @@ repeat: 
int f2fs_issue_flush(struct f2fs_sb_info *sbi)

{

	struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;

	struct flush_cmd *cmd;

	int ret;

	struct flush_cmd cmd;



	if (!test_opt(sbi, FLUSH_MERGE))

		return blkdev_issue_flush(sbi->sb->s_bdev, GFP_KERNEL, NULL);



	cmd = f2fs_kmem_cache_alloc(flush_cmd_slab, GFP_ATOMIC | __GFP_ZERO);

	init_completion(&cmd->wait);

	init_completion(&cmd.wait);

	cmd.next = NULL;



	spin_lock(&fcc->issue_lock);

	if (fcc->issue_list)

		fcc->issue_tail->next = cmd;

		fcc->issue_tail->next = &cmd;

	else

		fcc->issue_list = cmd;

	fcc->issue_tail = cmd;

		fcc->issue_list = &cmd;

	fcc->issue_tail = &cmd;

	spin_unlock(&fcc->issue_lock);



	if (!fcc->dispatch_list)

		wake_up(&fcc->flush_wait_queue);



	wait_for_completion(&cmd->wait);

	ret = cmd->ret;

	kmem_cache_free(flush_cmd_slab, cmd);

	return ret;

	wait_for_completion(&cmd.wait);



	return cmd.ret;

}



int create_flush_cmd_control(struct f2fs_sb_info *sbi)
@@ -2036,17 +2033,10 @@ int __init create_segment_manager_caches(void) 
			sizeof(struct discard_entry));

	if (!discard_entry_slab)

		return -ENOMEM;

	flush_cmd_slab = f2fs_kmem_cache_create("flush_command",

			sizeof(struct flush_cmd));

	if (!flush_cmd_slab) {

		kmem_cache_destroy(discard_entry_slab);

		return -ENOMEM;

	}

	return 0;

}



void destroy_segment_manager_caches(void)

{

	kmem_cache_destroy(discard_entry_slab);

	kmem_cache_destroy(flush_cmd_slab);

}