Messages in this thread | | | Date | Sun, 27 Nov 2022 17:45:02 +0800 | From | Ming Lei <> | Subject | Re: [PATCH RFC] scsi: core: remove unsed 'restarts' from scsi_device |
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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. > > > > 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.
I will look at this patch next week.
Can you investigate a bit the reason why perf boost is from this patch?
Thanks, Ming
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