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scoutfs: use larger percpu_counter batch

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The percpu_counter library merges the per-cpu counters with a shared
count when the per-cpu counter gets larger than a certain value.  The
default is very small, so we often end up taking a shared lock to update
the count.  Use a larger batch so that we take the lock less often.

Signed-off-by: Zach Brown <zab@versity.com>
This commit is contained in:
Zach Brown
2020-08-21 15:40:02 -07:00
committed by Zach Brown
parent ae97ffd6fc
commit b28acdf904
1 changed files with 14 additions and 4 deletions
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18
kmod/src/counters.h
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@@ -201,11 +201,21 @@ struct scoutfs_counters {
pcpu <= &SCOUTFS_SB(sb)->counters->LAST_COUNTER; \
pcpu++)
#define scoutfs_inc_counter(sb, which) \
percpu_counter_inc(&SCOUTFS_SB(sb)->counters->which)
/*
* We always read with _sum, we have no use for the shared count and
* certainly don't want to pay the cost of a shared lock to update it.
* The default batch of 32 make counter increments show up significantly
* in profiles.
*/
#define SCOUTFS_PCPU_COUNTER_BATCH (1 << 30)
#define scoutfs_add_counter(sb, which, cnt) \
percpu_counter_add(&SCOUTFS_SB(sb)->counters->which, cnt)
#define scoutfs_inc_counter(sb, which) \
__percpu_counter_add(&SCOUTFS_SB(sb)->counters->which, 1, \
SCOUTFS_PCPU_COUNTER_BATCH)
#define scoutfs_add_counter(sb, which, cnt) \
__percpu_counter_add(&SCOUTFS_SB(sb)->counters->which, cnt, \
SCOUTFS_PCPU_COUNTER_BATCH)
void __init scoutfs_init_counters(void);
int scoutfs_setup_counters(struct super_block *sb);