| Message ID | 20201116164322.GA7283@dongjoo-desktop (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-mq: modify hybrid sleep time to aggressive | expand |
diff --git a/block/blk-mq.c b/block/blk-mq.c index 1b25ec2fe9be..c3d578416899 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3749,8 +3749,7 @@ static unsigned long blk_mq_poll_nsecs(struct request_queue *q, return ret; if (q->poll_stat[bucket].nr_samples) - ret = (q->poll_stat[bucket].mean + 1) / 2; - + ret = (q->poll_stat[bucket].mean + 1) * 3 / 4; return ret; }
Current sleep time for hybrid polling is half of mean time. The 'half' sleep time is good for minimizing the cpu utilization. But, the problem is that its cpu utilization is still high. this patch can help to minimize the cpu utilization side. Below 1,2 is my test hardware sets. 1. Intel(R) Core(TM) i7-7700 CPU @ 3.60GHz + Samsung 970 pro 1Tb 2. Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz + INTEL SSDPED1D480GA 480G | Classic Polling | Hybrid Polling | this Patch ----------------------------------------------------------------- cpu util | IOPS(k) | cpu util | IOPS | cpu util | IOPS | ----------------------------------------------------------------- 1. 99.96 | 491 | 56.98 | 467 | 35.98 | 442 | ----------------------------------------------------------------- 2. 99.94 | 582 | 56.3 | 582 | 35.28 | 582 | cpu util means that sum of sys and user util. I used 4k rand read for this test. because that case is worst case of I/O performance side. below one is my fio setup. name=pollTest ioengine=pvsync2 hipri direct=1 size=100% randrepeat=0 time_based ramp_time=0 norandommap refill_buffers log_avg_msec=1000 log_max_value=1 group_reporting filename=/dev/nvme0n1 [rd_rnd_qd_1_4k_1w] bs=4k iodepth=32 numjobs=[num of cpus] rw=randread runtime=60 write_bw_log=bw_rd_rnd_qd_1_4k_1w write_iops_log=iops_rd_rnd_qd_1_4k_1w write_lat_log=lat_rd_rnd_qd_1_4k_1w Thanks Signed-off-by: Dongjoo Seo <commisori28@gmail.com> --- block/blk-mq.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)