From: David Ahern <dsahern@gmail.com>
To: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: "linux-perf-use." <linux-perf-users@vger.kernel.org>
Subject: Re: perf CPU profiling in Xen guest fail & workaround
Date: Wed, 29 Jul 2015 14:02:23 -0600 [thread overview]
Message-ID: <55B9314F.70800@gmail.com> (raw)
In-Reply-To: <CAE40pdfEv5aFDUf_ixp_mtq9T1NQ4sCkhS211EwaaeCg7a=8NQ@mail.gmail.com>
On 7/29/15 1:27 PM, Brendan Gregg wrote:
> Thanks, yes. This took me by surprise: I've been profiling different
> Xen guests for over a year, but this is the first time I've hit this.
>
> All my other Xen guests:
>
> # dmesg | grep Performance
> [ 0.058664] Performance Events: unsupported p6 CPU model 62 no PMU
> driver, software events only.
>
> This linux 4.1 Xen guest:
>
> # dmesg | grep Performance
> [ 0.258140] Performance Events: 16-deep LBR, IvyBridge events,
> Intel PMU driver.
yep and since the hypervisor lies perf has no means of knowing to
fallback to cpu-clock.
next prev parent reply other threads:[~2015-07-29 20:02 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-29 19:04 perf CPU profiling in Xen guest fail & workaround Brendan Gregg
2015-07-29 19:15 ` David Ahern
2015-07-29 19:27 ` Brendan Gregg
2015-07-29 20:02 ` David Ahern [this message]
2015-07-29 22:21 ` Andi Kleen
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