From: Like Xu <like.xu@linux.intel.com>
To: Eric Hankland <ehankland@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Jim Mattson <jmattson@google.com>,
Peter Shier <pshier@google.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Adjust counter sample period after a wrmsr
Date: Wed, 26 Feb 2020 11:04:02 +0800 [thread overview]
Message-ID: <8b48666a-c6a8-6dce-d784-424f5c447576@linux.intel.com> (raw)
In-Reply-To: <CAOyeoRX8kXD4nHGCLk=pV2EHS4t9wykV5tYDfgKkTLBcN5=GGw@mail.gmail.com>
On 2020/2/25 8:08, Eric Hankland wrote:
> Hi Like -
>
> Thanks for the feedback - is your recommendation to do the read and
> period change at the same time and only take the lock once or is there
> another way around this while still handling writes correctly?
For non-running counters(the most common situation), we have too many
chances to reflect their new periods. In this case, calling
perf_event_period() in the trap of counter msr is redundant and burdensome.
A better way is to check if this counter is running via
pmc_speculative_in_use (), and if so,
just trigger kvm_make_request(KVM_REQ_PMU, pmc->vcpu).
Thanks,
Like Xu
>
> Eric
>
prev parent reply other threads:[~2020-02-26 3:04 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-22 2:34 [PATCH] KVM: x86: Adjust counter sample period after a wrmsr Eric Hankland
2020-02-22 7:34 ` Paolo Bonzini
2020-02-24 6:56 ` Like Xu
2020-02-25 0:08 ` Eric Hankland
2020-02-26 3:04 ` Like Xu [this message]
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