Messages in this thread | | | Subject | Re: [PATCH V7 00/18] KVM: x86/pmu: Add *basic* support to enable guest PEBS via DS | From | "Zhu, Lingshan" <> | Date | Mon, 28 Jun 2021 15:53:40 +0800 |
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On 6/28/2021 3:49 PM, Wang, Wei W wrote: > On Friday, June 25, 2021 5:46 PM, Zhu, Lingshan wrote: >>> Only on the host? >>> I cannot use pebs unless try with "echo 0 > /proc/sys/kernel/watchdog" >>> both on the host and guest on ICX. >> Hi Xiangdong >> >> I guess you may run into the "cross-map" case(slow path below), so I think you >> can disable them both in host and guest to make PEBS work. >> > Hi Lingshan, could we also reproduce this issue? > > If the guest's watchdog takes away the virtual fixed counter, this will schedule the guest PEBS to use virtual PMC0. With the fast path (1:1 mapping), I think physical PMC0 is likely to be available for the guest PEBS emulation if no other host perf events are running. I think it is possible, even a virtual counter need a perf event scheduled on the host. This depends on the guest / host workloads.
Thanks, Zhu Lingshan > Best, > Wei
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