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Commit 77f4135f authored by Vivek Haldar's avatar Vivek Haldar Committed by Theodore Ts'o
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ext4: count hits/misses of extent cache and expose in sysfs 



The number of hits and misses for each filesystem is exposed in
/sys/fs/ext4/<dev>/extent_cache_{hits, misses}.

Tested: fsstress, manual checks.
Signed-off-by: default avatarVivek Haldar <haldar@google.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 93917411

fs/ext4/ext4.h

+3 −0
Original line number Diff line number Diff line
@@ -1144,6 +1144,9 @@ struct ext4_sb_info { 
	unsigned long s_ext_blocks;

	unsigned long s_ext_extents;

#endif

	/* ext4 extent cache stats */

	unsigned long extent_cache_hits;

	unsigned long extent_cache_misses;



	/* for buddy allocator */

	struct ext4_group_info ***s_group_info;

fs/ext4/extents.c

+6 −1
Original line number Diff line number Diff line
@@ -2035,6 +2035,7 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block, 
			struct ext4_extent *ex)

{

	struct ext4_ext_cache *cex;

	struct ext4_sb_info *sbi;

	int ret = 0;



	/*
@@ -2042,6 +2043,7 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block, 
	 */

	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);

	cex = &EXT4_I(inode)->i_cached_extent;

	sbi = EXT4_SB(inode->i_sb);



	/* has cache valid data? */

	if (cex->ec_len == 0)
@@ -2057,6 +2059,10 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block, 
		ret = 1;

	}

errout:

	if (!ret)

		sbi->extent_cache_misses++;

	else

		sbi->extent_cache_hits++;

	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);

	return ret;

}
@@ -3901,4 +3907,3 @@ int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo, 


	return error;

}

fs/ext4/super.c

+16 −0
Original line number Diff line number Diff line
@@ -2439,6 +2439,18 @@ static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a, 
			  EXT4_SB(sb)->s_sectors_written_start) >> 1)));

}



static ssize_t extent_cache_hits_show(struct ext4_attr *a,

				      struct ext4_sb_info *sbi, char *buf)

{

	return snprintf(buf, PAGE_SIZE, "%lu\n", sbi->extent_cache_hits);

}



static ssize_t extent_cache_misses_show(struct ext4_attr *a,

					struct ext4_sb_info *sbi, char *buf)

{

	return snprintf(buf, PAGE_SIZE, "%lu\n", sbi->extent_cache_misses);

}



static ssize_t inode_readahead_blks_store(struct ext4_attr *a,

					  struct ext4_sb_info *sbi,

					  const char *buf, size_t count)
@@ -2496,6 +2508,8 @@ static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store) 
EXT4_RO_ATTR(delayed_allocation_blocks);

EXT4_RO_ATTR(session_write_kbytes);

EXT4_RO_ATTR(lifetime_write_kbytes);

EXT4_RO_ATTR(extent_cache_hits);

EXT4_RO_ATTR(extent_cache_misses);

EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,

		 inode_readahead_blks_store, s_inode_readahead_blks);

EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
@@ -2511,6 +2525,8 @@ static struct attribute *ext4_attrs[] = { 
	ATTR_LIST(delayed_allocation_blocks),

	ATTR_LIST(session_write_kbytes),

	ATTR_LIST(lifetime_write_kbytes),

	ATTR_LIST(extent_cache_hits),

	ATTR_LIST(extent_cache_misses),

	ATTR_LIST(inode_readahead_blks),

	ATTR_LIST(inode_goal),

	ATTR_LIST(mb_stats),