From ea18e0f0a63af9064db3d4065d90fa743ae0991b Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Wed, 25 Mar 2020 16:07:06 +0300 Subject: block/diskstats: accumulate all per-cpu counters in one pass Reading /proc/diskstats iterates over all cpus for summing each field. It's faster to sum all fields in one pass. Hammering /proc/diskstats with fio shows 2x performance improvement: fio --name=test --numjobs=$JOBS --filename=/proc/diskstats \ --size=1k --bs=1k --fallocate=none --create_on_open=1 \ --time_based=1 --runtime=10 --invalidate=0 --group_report JOBS=1 JOBS=10 Before: 7k iops 64k iops After: 18k iops 120k iops Also this way code is more compact: add/remove: 1/0 grow/shrink: 0/2 up/down: 194/-1540 (-1346) Function old new delta part_stat_read_all - 194 +194 diskstats_show 1344 631 -713 part_stat_show 1219 392 -827 Total: Before=14966947, After=14965601, chg -0.01% Signed-off-by: Konstantin Khlebnikov Signed-off-by: Jens Axboe --- include/linux/genhd.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 13bb51f37b3f..b0c588d1aa29 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -380,9 +380,6 @@ static inline void free_part_stats(struct hd_struct *part) #endif /* CONFIG_SMP */ -#define part_stat_read_msecs(part, which) \ - div_u64(part_stat_read(part, nsecs[which]), NSEC_PER_MSEC) - #define part_stat_read_accum(part, field) \ (part_stat_read(part, field[STAT_READ]) + \ part_stat_read(part, field[STAT_WRITE]) + \ -- cgit v1.2.3