Messages in this thread | | | Subject | Re: [PATCH RFC] scsi: core: remove unsed 'restarts' from scsi_device | From | Yu Kuai <> | Date | Mon, 28 Nov 2022 11:35:18 +0800 |
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在 2022/11/28 11:27, Ming Lei 写道: > On Sat, Nov 26, 2022 at 04:54:46PM +0800, Yu Kuai wrote: >> Hi, >> >> 在 2022/11/18 19:30, Yu Kuai 写道: >>> From: Yu Kuai <yukuai3@huawei.com> >>> >>> During code review, I found that 'restarts' is not useful anymore after >>> the following commits: >>> >>> 1) commit ab3cee3762e5 ("blk-mq: In blk_mq_dispatch_rq_list() "no budget" >>> is a reason to kick") >>> 2) commit d3b38596875d ("blk-mq: run queue no matter whether the request >>> is the last request") >>> 3) commit 673235f91531 ("scsi: core: Fix race between handling STS_RESOURCE >>> and completion") >>> >>> Now that if get budget ever failed, block layer will make sure to >>> trigger new run queue for the hctx. Hence there is no need to run queue >>> from scsi layer in this case. >>> > > But scsi_run_queue_async() needs to run all hw queue because budget is > actually LUN/request queue wide.
Why the hw queue need to run if get budget never failed in this hw queue?
> >> >> Does anyone has suggestions about this patch? >> >> More info why I tried to remove this: >> >> while testing megaraid with 4 nvme with none elevator, the default >> queue_depth is 128, while I test it with fio 128 jobs and 1 iodepth, >> bw is about 4Gib/s, however, if I test with 128 jobs and 2 iodepth, >> bw is decreased to about 0.8Gib/s, and with this patch applied, >> bw can stay 4Gib/s in the later case. > > What is .can_queue and nr_hw_queues in your setting? test cmd: fio -name=0 -ioengine=libaio -direct=1 -group_reporting=1 -randseed=2022 -rwmixread=70 -refill_buffers -filename=/dev/sdg -numjobs=128 -size=1TB -runtime=60s -bs=4k -iodepth=2 -rw=randwrite
test environment: arm64 Kunpeng-920, 128 cpu megaraid with 4 NVMEs, 128 hctx and queue_depth is 128
> > > > thanks, > Ming > > . >
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