-----Original Message----- From: Martin Wilck [mailto:mwilck@xxxxxxxx] Subject: Re: [PATCH] scsi: scsi_host_queue_ready: increase busy count early > > > Confirmed my suspicions - it looks like the host is sent more commands > than it can handle. We would need many disks to see this issue though, > which you have. > > So for stable kernels, 6eb045e092ef is not in 5.4 . Next is 5.10, and > I suppose it could be simply fixed by setting .host_tagset in scsi > host template there. > > Thanks, > John > -- > Don: Even though this works for current kernels, what would chances of > this getting back-ported to 5.9 or even further? > > Otherwise the original patch smartpqi_fix_host_qdepth_limit would > correct this issue for older kernels. True. However this is 5.12 material, so we shouldn't be bothered by that here. For 5.5 up to 5.9, you need a workaround. But I'm unsure whether smartpqi_fix_host_qdepth_limit would be the solution. You could simply divide can_queue by nr_hw_queues, as suggested before, or even simpler, set nr_hw_queues = 1. How much performance would that cost you? Don: For my HBA disk tests... Dividing can_queue / nr_hw_queues is about a 40% drop. ~380K - 400K IOPS Setting nr_hw_queues = 1 results in a 1.5 X gain in performance. ~980K IOPS Setting host_tagset = 1 ~640K IOPS So, it seem that setting nr_hw_queues = 1 results in the best performance. Is this expected? Would this also be true for the future? Thanks, Don Brace Below is my setup. --- [3:0:0:0] disk HP EG0900FBLSK HPD7 /dev/sdd [3:0:1:0] disk HP EG0900FBLSK HPD7 /dev/sde [3:0:2:0] disk HP EG0900FBLSK HPD7 /dev/sdf [3:0:3:0] disk HP EH0300FBQDD HPD5 /dev/sdg [3:0:4:0] disk HP EG0900FDJYR HPD4 /dev/sdh [3:0:5:0] disk HP EG0300FCVBF HPD9 /dev/sdi [3:0:6:0] disk HP EG0900FBLSK HPD7 /dev/sdj [3:0:7:0] disk HP EG0900FBLSK HPD7 /dev/sdk [3:0:8:0] disk HP EG0900FBLSK HPD7 /dev/sdl [3:0:9:0] disk HP MO0200FBRWB HPD9 /dev/sdm [3:0:10:0] disk HP MM0500FBFVQ HPD8 /dev/sdn [3:0:11:0] disk ATA MM0500GBKAK HPGC /dev/sdo [3:0:12:0] disk HP EG0900FBVFQ HPDC /dev/sdp [3:0:13:0] disk HP VO006400JWZJT HP00 /dev/sdq [3:0:14:0] disk HP VO015360JWZJN HP00 /dev/sdr [3:0:15:0] enclosu HP D3700 5.04 - [3:0:16:0] enclosu HP D3700 5.04 - [3:0:17:0] enclosu HPE Smart Adapter 3.00 - [3:1:0:0] disk HPE LOGICAL VOLUME 3.00 /dev/sds [3:2:0:0] storage HPE P408e-p SR Gen10 3.00 - ----- [global] ioengine=libaio ; rw=randwrite ; percentage_random=40 rw=write size=100g bs=4k direct=1 ramp_time=15 ; filename=/mnt/fio_test ; cpus_allowed=0-27 iodepth=4096 [/dev/sdd] [/dev/sde] [/dev/sdf] [/dev/sdg] [/dev/sdh] [/dev/sdi] [/dev/sdj] [/dev/sdk] [/dev/sdl] [/dev/sdm] [/dev/sdn] [/dev/sdo] [/dev/sdp] [/dev/sdq] [/dev/sdr] Distribution kernels would be yet another issue, distros can backport host_tagset and get rid of the issue. Regards Martin
