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Commit 520f897a authored by Yang Guo's avatar Yang Guo Committed by Theodore Ts'o
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ext4: use percpu_counters for extent_status cache hits/misses 



@es_stats_cache_hits and @es_stats_cache_misses are accessed frequently in
ext4_es_lookup_extent function, it would influence the ext4 read/write
performance in NUMA system. Let's optimize it using percpu_counter,
it is profitable for the performance.

The test command is as below:
fio -name=randwrite -numjobs=8 -filename=/mnt/test1 -rw=randwrite
-ioengine=libaio -direct=1 -iodepth=64 -sync=0 -norandommap
-group_reporting -runtime=120 -time_based -bs=4k -size=5G

And the result is better 10% than the initial implement:
without the patch，IOPS=197k, BW=770MiB/s (808MB/s)(90.3GiB/120002msec)
with the patch,  IOPS=218k, BW=852MiB/s (894MB/s)(99.9GiB/120002msec)

Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: default avatarYang Guo <guoyang2@huawei.com>
Signed-off-by: default avatarShaokun Zhang <zhangshaokun@hisilicon.com>
parent 7727ae52

fs/ext4/extents_status.c

+24 −13
Original line number Diff line number Diff line
@@ -948,7 +948,7 @@ int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk, 
		es->es_pblk = es1->es_pblk;

		if (!ext4_es_is_referenced(es1))

			ext4_es_set_referenced(es1);

		stats->es_stats_cache_hits++;

		percpu_counter_inc(&stats->es_stats_cache_hits);

		if (next_lblk) {

			node = rb_next(&es1->rb_node);

			if (node) {
@@ -959,7 +959,7 @@ int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk, 
				*next_lblk = 0;

		}

	} else {

		stats->es_stats_cache_misses++;

		percpu_counter_inc(&stats->es_stats_cache_misses);

	}



	read_unlock(&EXT4_I(inode)->i_es_lock);
@@ -1586,9 +1586,9 @@ int ext4_seq_es_shrinker_info_show(struct seq_file *seq, void *v) 
	seq_printf(seq, "stats:\n  %lld objects\n  %lld reclaimable objects\n",

		   percpu_counter_sum_positive(&es_stats->es_stats_all_cnt),

		   percpu_counter_sum_positive(&es_stats->es_stats_shk_cnt));

	seq_printf(seq, "  %lu/%lu cache hits/misses\n",

		   es_stats->es_stats_cache_hits,

		   es_stats->es_stats_cache_misses);

	seq_printf(seq, "  %lld/%lld cache hits/misses\n",

		   percpu_counter_sum_positive(&es_stats->es_stats_cache_hits),

		   percpu_counter_sum_positive(&es_stats->es_stats_cache_misses));

	if (inode_cnt)

		seq_printf(seq, "  %d inodes on list\n", inode_cnt);
@@ -1615,35 +1615,46 @@ int ext4_es_register_shrinker(struct ext4_sb_info *sbi) 
	sbi->s_es_nr_inode = 0;

	spin_lock_init(&sbi->s_es_lock);

	sbi->s_es_stats.es_stats_shrunk = 0;

	sbi->s_es_stats.es_stats_cache_hits = 0;

	sbi->s_es_stats.es_stats_cache_misses = 0;

	err = percpu_counter_init(&sbi->s_es_stats.es_stats_cache_hits, 0,

				  GFP_KERNEL);

	if (err)

		return err;

	err = percpu_counter_init(&sbi->s_es_stats.es_stats_cache_misses, 0,

				  GFP_KERNEL);

	if (err)

		goto err1;

	sbi->s_es_stats.es_stats_scan_time = 0;

	sbi->s_es_stats.es_stats_max_scan_time = 0;

	err = percpu_counter_init(&sbi->s_es_stats.es_stats_all_cnt, 0, GFP_KERNEL);

	if (err)

		return err;

		goto err2;

	err = percpu_counter_init(&sbi->s_es_stats.es_stats_shk_cnt, 0, GFP_KERNEL);

	if (err)

		goto err1;

		goto err3;



	sbi->s_es_shrinker.scan_objects = ext4_es_scan;

	sbi->s_es_shrinker.count_objects = ext4_es_count;

	sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;

	err = register_shrinker(&sbi->s_es_shrinker);

	if (err)

		goto err2;

		goto err4;



	return 0;



err2:

err4:

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);

err1:

err3:

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);

err2:

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_misses);

err1:

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_hits);

	return err;

}



void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)

{

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_hits);

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_misses);

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);

	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);

	unregister_shrinker(&sbi->s_es_shrinker);

fs/ext4/extents_status.h

+2 −2
Original line number Diff line number Diff line
@@ -70,8 +70,8 @@ struct ext4_es_tree { 


struct ext4_es_stats {

	unsigned long es_stats_shrunk;

	unsigned long es_stats_cache_hits;

	unsigned long es_stats_cache_misses;

	struct percpu_counter es_stats_cache_hits;

	struct percpu_counter es_stats_cache_misses;

	u64 es_stats_scan_time;

	u64 es_stats_max_scan_time;

	struct percpu_counter es_stats_all_cnt;