Messages in this thread | | | Subject | Re: [PATCH v3 0/9] Parallel CPU bringup for x86_64 | From | Tom Lendacky <> | Date | Thu, 16 Dec 2021 13:55:36 -0600 |
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On 12/16/21 1:52 PM, David Woodhouse wrote: > On Thu, 2021-12-16 at 10:27 -0600, Tom Lendacky wrote: >> On 12/15/21 8:56 AM, David Woodhouse wrote: >> >>> Doing the INIT/SIPI/SIPI in parallel for all APs and *then* waiting for >>> them shaves about 80% off the AP bringup time on a 96-thread socket >>> Skylake box (EC2 c5.metal) — from about 500ms to 100ms. >>> >>> There are more wins to be had with further parallelisation, but this is >>> the simple part. >> >> I applied this series and began booting a regular non-SEV guest and hit a >> failure at 39 vCPUs. No panic or warning, just a reset and OVMF was >> executing again. I'll try to debug what's going, but not sure how quickly >> I'll arrive at anything. > > I've pushed the SEV-ES fix to > https://git.infradead.org/users/dwmw2/linux.git/shortlog/refs/heads/parallel-5.16 > and in doing so I've moved the 'no_parallel_bringup' command line > argument earlier in the series, to Thomas's "Support parallel startup > of secondary CPUs" commit (now 191f0899757). It would be interesting to > see if you can reproduce with just that much, both with and with > no_parallel_bringup. And then whether the subsequent commit that > actually enables the parallel INIT/SIPI/SIPI actually makes the > difference? >
I'll pull it down and give it try.
Thanks, Tom
> Thanks! >
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