Messages in this thread | | | Subject | Re: [PATCH RFT] blk-mq: optimize queue tag busy iter for shared_tags | From | John Garry <> | Date | Wed, 22 Dec 2021 12:34:13 +0000 |
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On 22/12/2021 12:06, Kashyap Desai wrote: >> But I did not think that my patch would help mpi3mr since it does not use >> host_tagset. > Internally we are testing performance check for mpi3mr. We want to make sure > performance is not impacted due to shared host_tagset before we apply the > feature.
Hmmm... I thought that you said previously that it was not necessary for this HW. But I am not familiar with the driver or HW.
As an aside, I assume that this driver uses none IO sched by default, but drivers using host_tagset use mq-deadline – I’m not sure if that is what you want.
> >>> We can drop >>> request of this RFT since I tested above series and it serve the same >>> purpose. >> ok, fine. >> >> And just to confirm, do you now think that we need to fix any older kernel >> with some backport of my changes? I think that we would just need to >> consider 5.16 (when it becomes stable), 5.15, and and 5.10 > It need full patch set (below) + associated fixes. > [1] " blk-mq: Use shared tags for shared sbitmap support" Commit - > e155b0c238b20f0a866f4334d292656665836c8a > > Below commit cannot go to stable without [1]. > https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=for-5.17/block&id=fea9f92f1748083cb82049ed503be30c3d3a9b69 > > I am not sure if stable requirement fits in this case. I mean large > patch-set is OK ?
The two other patches in the series wouldn't need to be backported, so it should be possible. You would just need a very good reason, though. And we would need to know whether 5.10 and 5.15 are required - they use shared sbitmap. As I mentioned a few times, contention in blk_mq_queue_tag_busy_iter() and callees would not be so high as blk_mq_tags.lock and blk_mq_tags.rqs are not shared there.
Thanks, John
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