Re: [GIT PULL] perf changes for v3.8

From: David Ahern
Date: Sun Dec 23 2012 - 18:17:51 EST

On 12/23/12 2:23 AM, Gleb Natapov wrote:
Your patch alone was not enough. Start here:

I cannot reproduce this failure. I reverted 20b279ddb38c and ran "perf
record -e cycles:ppG" while guest was running. Admittedly I ran the test
for a short time, but without disabling PEBS during the guest entry this
was enough to crash a guest.

In the beginning (without any patches) VMs crashed fairly quickly. With your patch it took longer, but I was able to consistently crash VMs. The thread notes server info (processor, OS) and VM versions as well as load used for the tests -- a cpu bound process (openssl), disk bound (dd) and network (netperf).

What about forcing exclude_guest on an event that
has precise flag set without reporting error to userspace?

That's up to the perf maintainers -- Ingo, Peter, Arnaldo. Personally, I don't like it since kernel side is changing the user request.

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