From: Andi Kleen <andi@firstfloor.org>
To: David Ahern <dsahern@gmail.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>,
"linux-perf-use." <linux-perf-users@vger.kernel.org>
Subject: Re: perf CPU profiling in Xen guest fail & workaround
Date: Wed, 29 Jul 2015 15:21:54 -0700 [thread overview]
Message-ID: <874mkm8v0d.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <55B92661.7010309@gmail.com> (David Ahern's message of "Wed, 29 Jul 2015 13:15:45 -0600")
David Ahern <dsahern@gmail.com> writes:
>
> It's a known problem with VMs (Solaris based ldoms and apparently xen
> guests as examples). The hypervisor tells perf it has a PMU (see dmesg
> | grep Performance) but does not really implement it (no NMIs for
> example).
Actually Xen has a PMU model. I've never tested it, but from a quick
source review some time ago it seemed reasonable for Arch Perfmon v1,
when disabled.
If something doesn't work you should report it to the Xen people
BTW sampling works with KVM's PMU model; I'm using that occasionally.
-Andi
--
ak@linux.intel.com -- Speaking for myself only
prev parent reply other threads:[~2015-07-29 22:21 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
2015-07-29 22:21 ` Andi Kleen [this message]
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