Messages in this thread | | | Subject | Re: [PATCH RFC 1/1] genirq: Make threaded handler use irq affinity for managed interrupt | From | John Garry <> | Date | Fri, 20 Dec 2019 15:38:24 +0000 |
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>> We've got some more results and it looks promising. >> >> So with your patch we get a performance boost of 3180.1K -> 3294.9K >> IOPS in the D06 SAS env. Then when we change the driver to use >> threaded interrupt handler (mainline currently uses tasklet), we get a >> boost again up to 3415K IOPS. >> >> Now this is essentially the same figure we had with using threaded >> handler + the gen irq change in spreading the handler CPU affinity. We >> did also test your patch + gen irq change and got a performance drop, >> to 3347K IOPS. >> >> So tentatively I'd say your patch may be all we need. > > OK. > >> FYI, here is how the effective affinity is looking for both SAS >> controllers with your patch: >> >> 74:02.0 >> irq 81, cpu list 24-29, effective list 24 cq >> irq 82, cpu list 30-35, effective list 30 cq > > Cool. > > [...] > >> As for your patch itself, I'm still concerned of possible regressions >> if we don't apply this effective interrupt affinity spread policy to >> only managed interrupts. > > I'll try and revise that as I post the patch, probably at some point > between now and Christmas. I still think we should find a way to > address this for the D05 SAS driver though, maybe by managing the > affinity yourself in the driver. But this requires experimentation.
I've already done something experimental for the driver to manage the affinity, and performance is generally much better:
https://github.com/hisilicon/kernel-dev/commit/e15bd404ed1086fed44da34ed3bd37a8433688a7
But I still think it's wise to only consider managed interrupts for now.
> >> JFYI, about NVMe CPU lockup issue, there are 2 works on going here: >> >> https://lore.kernel.org/linux-nvme/20191209175622.1964-1-kbusch@kernel.org/T/#t >> >> >> https://lore.kernel.org/linux-block/20191218071942.22336-1-ming.lei@redhat.com/T/#t >> > > I've also managed to trigger some of them now that I have access to > a decent box with nvme storage.
I only have 2x NVMe SSDs when this occurs - I should not be hitting this...
Out of curiosity, have you tried > with the SMMU disabled? I'm wondering whether we hit some livelock > condition on unmapping buffers...
No, but I can give it a try. Doing that should lower the CPU usage, though, so maybe masks the issue - probably not.
Much appreciated, John
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