ext4: Add per CR extent scanned counter

This gives better visibility into the number of extents scanned in each
particular CR. For example, this information can be used to see how out
block group scanning logic is performing when the BG is fragmented.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/55bb6d80f6e22ed2a5a830aa045572bdffc8b1b9.1685449706.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 914475cbb0605c474672e3e5e1e55604f0b83354..34ec65126ea778ef1280ffe106f3da12ec81a214 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1555,6 +1555,7 @@ 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_cX_ex_scanned[EXT4_MB_NUM_CRS];  /* total extents scanned */
        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 */

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4359280d2fa79cd72d66e54b61651f3afa4f3b34..e28731426ee54bd6282381175b1796f7222e3fbe 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2103,6 +2103,7 @@ static void ext4_mb_measure_extent(struct ext4_allocation_context *ac,
        BUG_ON(ac->ac_status != AC_STATUS_CONTINUE);
 
        ac->ac_found++;
+       ac->ac_cX_found[ac->ac_criteria]++;
 
        /*
         * The special case - take what you catch first
@@ -2277,6 +2278,7 @@ void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
                        break;
                }
                ac->ac_found++;
+               ac->ac_cX_found[ac->ac_criteria]++;
 
                ac->ac_b_ex.fe_len = 1 << i;
                ac->ac_b_ex.fe_start = k << i;
@@ -2392,6 +2394,7 @@ void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
                        max = mb_find_extent(e4b, i, stripe, &ex);
                        if (max >= stripe) {
                                ac->ac_found++;
+                               ac->ac_cX_found[ac->ac_criteria]++;
                                ex.fe_logical = 0xDEADF00D; /* debug value */
                                ac->ac_b_ex = ex;
                                ext4_mb_use_best_found(ac, e4b);
@@ -2929,6 +2932,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
        seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[CR0]));
        seq_printf(seq, "\t\tgroups_considered: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_groups_considered[CR0]));
+       seq_printf(seq, "\t\textents_scanned: %u\n", atomic_read(&sbi->s_bal_cX_ex_scanned[CR0]));
        seq_printf(seq, "\t\tuseless_loops: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_failed[CR0]));
        seq_printf(seq, "\t\tbad_suggestions: %u\n",
@@ -2938,6 +2942,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
        seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[CR1]));
        seq_printf(seq, "\t\tgroups_considered: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_groups_considered[CR1]));
+       seq_printf(seq, "\t\textents_scanned: %u\n", atomic_read(&sbi->s_bal_cX_ex_scanned[CR1]));
        seq_printf(seq, "\t\tuseless_loops: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_failed[CR1]));
        seq_printf(seq, "\t\tbad_suggestions: %u\n",
@@ -2947,6 +2952,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
        seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[CR2]));
        seq_printf(seq, "\t\tgroups_considered: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_groups_considered[CR2]));
+       seq_printf(seq, "\t\textents_scanned: %u\n", atomic_read(&sbi->s_bal_cX_ex_scanned[CR2]));
        seq_printf(seq, "\t\tuseless_loops: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_failed[CR2]));
 
@@ -2954,6 +2960,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
        seq_printf(seq, "\t\thits: %llu\n", atomic64_read(&sbi->s_bal_cX_hits[CR3]));
        seq_printf(seq, "\t\tgroups_considered: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_groups_considered[CR3]));
+       seq_printf(seq, "\t\textents_scanned: %u\n", atomic_read(&sbi->s_bal_cX_ex_scanned[CR3]));
        seq_printf(seq, "\t\tuseless_loops: %llu\n",
                   atomic64_read(&sbi->s_bal_cX_failed[CR3]));
        seq_printf(seq, "\textents_scanned: %u\n", atomic_read(&sbi->s_bal_ex_scanned));
@@ -4393,7 +4400,12 @@ static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
                atomic_add(ac->ac_b_ex.fe_len, &sbi->s_bal_allocated);
                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);
+               for (int i=0; i<EXT4_MB_NUM_CRS; i++) {
+                       atomic_add(ac->ac_cX_found[i], &sbi->s_bal_cX_ex_scanned[i]);
+               }
+
                atomic_add(ac->ac_groups_scanned, &sbi->s_bal_groups_scanned);
                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)

diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 24b666e558f12b434fe5ca360498897f39f20bf8..acfdc204e15d24cec02e4b64d79dec107092b909 100644 (file)
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -184,6 +184,7 @@ struct ext4_allocation_context {
        __u16 ac_groups_scanned;
        __u16 ac_groups_linear_remaining;
        __u16 ac_found;
+       __u16 ac_cX_found[EXT4_MB_NUM_CRS];
        __u16 ac_tail;
        __u16 ac_buddy;
        __u8 ac_status;