Adding Damien who wrote this code. On Wed, Nov 18, 2020 at 09:47:46AM +0900, Dongjoo Seo wrote: > 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@xxxxxxxxx> > --- > block/blk-mq.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > 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; > } > > -- > 2.17.1 > ---end quoted text---
