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Message-Id: <20210226193612.1199321-3-harshadshirwadkar@gmail.com>
Date: Fri, 26 Feb 2021 11:36:09 -0800
From: Harshad Shirwadkar <harshadshirwadkar@...il.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, adilger@...ger.ca,
Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: [PATCH v3 2/5] ext4: add mballoc stats proc file
Add new stats for measuring the performance of mballoc. This patch is
forked from Artem Blagodarenko's work that can be found here:
https://github.com/lustre/lustre-release/blob/master/ldiskfs/kernel_patches/patches/rhel8/ext4-simple-blockalloc.patch
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Reviewed-by: Andreas Dilger <adilger@...ger.ca>
---
fs/ext4/ext4.h | 4 ++++
fs/ext4/mballoc.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++-
fs/ext4/mballoc.h | 1 +
fs/ext4/sysfs.c | 2 ++
4 files changed, 57 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index cb0724b87d54..3e906a3d553a 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1549,6 +1549,8 @@ struct ext4_sb_info {
atomic_t s_bal_success; /* we found long enough chunks */
atomic_t s_bal_allocated; /* in blocks */
atomic_t s_bal_ex_scanned; /* total extents scanned */
+ atomic_t s_bal_groups_considered; /* number of groups considered */
+ atomic_t s_bal_groups_scanned; /* number of groups scanned */
atomic_t s_bal_goals; /* goal hits */
atomic_t s_bal_breaks; /* too long searches */
atomic_t s_bal_2orders; /* 2^order hits */
@@ -1558,6 +1560,7 @@ struct ext4_sb_info {
atomic_t s_mb_preallocated;
atomic_t s_mb_discarded;
atomic_t s_lock_busy;
+ atomic64_t s_bal_cX_failed[4]; /* cX loop didn't find blocks */
/* locality groups */
struct ext4_locality_group __percpu *s_locality_groups;
@@ -2808,6 +2811,7 @@ int __init ext4_fc_init_dentry_cache(void);
extern const struct seq_operations ext4_mb_seq_groups_ops;
extern long ext4_mb_stats;
extern long ext4_mb_max_to_scan;
+extern int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset);
extern int ext4_mb_init(struct super_block *);
extern int ext4_mb_release(struct super_block *);
extern ext4_fsblk_t ext4_mb_new_blocks(handle_t *,
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 07b78a3cc421..92c4edaa1afc 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2146,6 +2146,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
ext4_grpblk_t free;
int ret = 0;
+ ac->ac_groups_considered++;
if (should_lock)
ext4_lock_group(sb, group);
free = grp->bb_free;
@@ -2420,6 +2421,9 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
if (ac->ac_status != AC_STATUS_CONTINUE)
break;
}
+ /* Processed all groups and haven't found blocks */
+ if (sbi->s_mb_stats && i == ngroups)
+ atomic64_inc(&sbi->s_bal_cX_failed[cr]);
}
if (ac->ac_b_ex.fe_len > 0 && ac->ac_status != AC_STATUS_FOUND &&
@@ -2548,6 +2552,48 @@ const struct seq_operations ext4_mb_seq_groups_ops = {
.show = ext4_mb_seq_groups_show,
};
+int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
+{
+ struct super_block *sb = (struct super_block *)seq->private;
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+
+ seq_puts(seq, "mballoc:\n");
+ if (!sbi->s_mb_stats) {
+ seq_puts(seq, "\tmb stats collection turned off.\n");
+ seq_puts(seq, "\tTo enable, please write \"1\" to sysfs file mb_stats.\n");
+ return 0;
+ }
+ seq_printf(seq, "\treqs: %u\n", atomic_read(&sbi->s_bal_reqs));
+ seq_printf(seq, "\tsuccess: %u\n", atomic_read(&sbi->s_bal_success));
+
+ seq_printf(seq, "\tgroups_scanned: %u\n", atomic_read(&sbi->s_bal_groups_scanned));
+ seq_printf(seq, "\tgroups_considered: %u\n", atomic_read(&sbi->s_bal_groups_considered));
+ seq_printf(seq, "\textents_scanned: %u\n", atomic_read(&sbi->s_bal_ex_scanned));
+ seq_printf(seq, "\t\tgoal_hits: %u\n", atomic_read(&sbi->s_bal_goals));
+ seq_printf(seq, "\t\t2^n_hits: %u\n", atomic_read(&sbi->s_bal_2orders));
+ seq_printf(seq, "\t\tbreaks: %u\n", atomic_read(&sbi->s_bal_breaks));
+ seq_printf(seq, "\t\tlost: %u\n", atomic_read(&sbi->s_mb_lost_chunks));
+
+ seq_printf(seq, "\tuseless_c0_loops: %llu\n",
+ (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[0]));
+ seq_printf(seq, "\tuseless_c1_loops: %llu\n",
+ (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[1]));
+ seq_printf(seq, "\tuseless_c2_loops: %llu\n",
+ (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[2]));
+ seq_printf(seq, "\tuseless_c3_loops: %llu\n",
+ (unsigned long long)atomic64_read(&sbi->s_bal_cX_failed[3]));
+ seq_printf(seq, "\tbuddies_generated: %u/%u\n",
+ atomic_read(&sbi->s_mb_buddies_generated),
+ ext4_get_groups_count(sb));
+ seq_printf(seq, "\tbuddies_time_used: %llu\n",
+ atomic64_read(&sbi->s_mb_generation_time));
+ seq_printf(seq, "\tpreallocated: %u\n",
+ atomic_read(&sbi->s_mb_preallocated));
+ seq_printf(seq, "\tdiscarded: %u\n",
+ atomic_read(&sbi->s_mb_discarded));
+ return 0;
+}
+
static struct kmem_cache *get_groupinfo_cache(int blocksize_bits)
{
int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE;
@@ -2968,9 +3014,10 @@ int ext4_mb_release(struct super_block *sb)
atomic_read(&sbi->s_bal_reqs),
atomic_read(&sbi->s_bal_success));
ext4_msg(sb, KERN_INFO,
- "mballoc: %u extents scanned, %u goal hits, "
+ "mballoc: %u extents scanned, %u groups scanned, %u goal hits, "
"%u 2^N hits, %u breaks, %u lost",
atomic_read(&sbi->s_bal_ex_scanned),
+ atomic_read(&sbi->s_bal_groups_scanned),
atomic_read(&sbi->s_bal_goals),
atomic_read(&sbi->s_bal_2orders),
atomic_read(&sbi->s_bal_breaks),
@@ -3579,6 +3626,8 @@ static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
if (ac->ac_b_ex.fe_len >= ac->ac_o_ex.fe_len)
atomic_inc(&sbi->s_bal_success);
atomic_add(ac->ac_found, &sbi->s_bal_ex_scanned);
+ atomic_add(ac->ac_groups_scanned, &sbi->s_bal_groups_scanned);
+ atomic_add(ac->ac_groups_considered, &sbi->s_bal_groups_considered);
if (ac->ac_g_ex.fe_start == ac->ac_b_ex.fe_start &&
ac->ac_g_ex.fe_group == ac->ac_b_ex.fe_group)
atomic_inc(&sbi->s_bal_goals);
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index e75b4749aa1c..7597330dbdf8 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -161,6 +161,7 @@ struct ext4_allocation_context {
/* copy of the best found extent taken before preallocation efforts */
struct ext4_free_extent ac_f_ex;
+ __u32 ac_groups_considered;
__u16 ac_groups_scanned;
__u16 ac_found;
__u16 ac_tail;
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 075aa3a19ff5..59ca9d73b42f 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -521,6 +521,8 @@ int ext4_register_sysfs(struct super_block *sb)
ext4_fc_info_show, sb);
proc_create_seq_data("mb_groups", S_IRUGO, sbi->s_proc,
&ext4_mb_seq_groups_ops, sb);
+ proc_create_single_data("mb_stats", 0444, sbi->s_proc,
+ ext4_seq_mb_stats_show, sb);
}
return 0;
}
--
2.30.1.766.gb4fecdf3b7-goog
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