From: David Ahern <dsahern@gmail.com>
To: Peipei Wang <wangpeipei.90@gmail.com>
Cc: perf group <linux-perf-users@vger.kernel.org>
Subject: Re: Can perf be used to record cycles or instructions on Virtual Machine
Date: Wed, 26 Jun 2013 13:20:50 -0600 [thread overview]
Message-ID: <51CB3F12.4030206@gmail.com> (raw)
In-Reply-To: <CAEuYUeoCAOJAP4xvKWsFf4e-VJ0BuooO=i8_1qadva-1YFii5w@mail.gmail.com>
On 6/26/13 1:13 PM, Peipei Wang wrote:
> Hi, all.
> I got a new problem.
>
> When I use perf to get CPI( cycles per instruction) on a Virtual
> Machine, I receive the message that
> cycles and instructions are not supported.
>
> However, other events like page-faults or context-switches can be
> supported well.
> I don't know why. So I guess I can't user perf to record a certain
> sort of performance events on Virtual Machine.
>
> Is my guess correct?? What kind of performance events in hell aren't
> supported?
KVM supports a virtual PMU which uses perf_events host side. I believe
it went into v3.2, so a host kernel version of 3.2 and greater will have it.
You also need an updated qemu version to set the cpuid bits. I forget
which version exactly - 1.2 should work.
David
prev parent reply other threads:[~2013-06-26 19:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-26 19:13 Can perf be used to record cycles or instructions on Virtual Machine Peipei Wang
2013-06-26 19:20 ` David Ahern [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=51CB3F12.4030206@gmail.com \
--to=dsahern@gmail.com \
--cc=linux-perf-users@vger.kernel.org \
--cc=wangpeipei.90@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.