Messages in this thread | | | Date | Wed, 27 Sep 2023 13:33:12 +0200 | From | Peter Zijlstra <> | Subject | Re: [Patch v4 07/13] perf/x86: Add constraint for guest perf metrics event |
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On Wed, Sep 27, 2023 at 11:31:18AM +0800, Dapeng Mi wrote: > When guest wants to use PERF_METRICS MSR, a virtual metrics event needs > to be created in the perf subsystem so that the guest can have exclusive > ownership of the PERF_METRICS MSR.
Urgh, can someone please remind me how all that is supposed to work again? The guest is just a task that wants the event. If the host creates a CPU event, then that gets scheduled with higher priority and the task looses out, no joy.
So you cannot guarantee the guest gets anything.
That is, I remember we've had this exact problem before, but I keep forgetting how this all is supposed to work. I don't use this virt stuff (and every time I try qemu arguments defeat me and I give up in disgust).
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