All of lore.kernel.org
 help / color / mirror / Atom feed
From: Sebastian Hetze <s.hetze@linux-ag.com>
To: Sebastian Hetze <s.hetze@linux-ag.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	Avi Kivity <avi@redhat.com>,
	kvm@vger.kernel.org
Subject: Re: Strange CPU usage pattern in SMP guest
Date: Mon, 5 Apr 2010 23:24:50 +0200	[thread overview]
Message-ID: <20100405212450.CEE7F30301D3@mail.linux-ag.de> (raw)
In-Reply-To: <20100330082743.49A113030135@mail.linux-ag.de>

On Tue, Mar 30, 2010 at 10:27:43AM +0200, Sebastian Hetze wrote:
> With this patch applied, the system runs without hrtimer messages since
> 5 days and the timer iterrupts look fine.
> 
> Actually, when restarting the system with the hrtimer patch applied,
> we also changed the BIOS setting to disable Intel SmartStep on the host.
> Since there are no hrtimer messages at all, it might be that the SmartStep
> CPU frequency adjustment is the real cause for the slow interrupts in
> the KVM guest. Anyone else experienced these problems?

Back with SmartStep enabled, we get "hrtimer: interrupt took 119986041 ns"
so it really looks like this SmartStep feature is the actual cause for
the interrupts to be delayed in the first place.

The system continues to run correctly so far, so the patch does fix the 
problems caused by these delayed interrupts.

Thanx alot & best regards,

  Sebastian

      parent reply	other threads:[~2010-04-05 21:24 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-21  0:13 Strange CPU usage pattern in SMP guest Sebastian Hetze
2010-03-21 10:09 ` Avi Kivity
2010-03-21 12:02   ` Sebastian Hetze
     [not found]   ` <20100321120236.55228A0015@mail.linux-ag.de>
2010-03-21 12:19     ` Avi Kivity
2010-03-21 14:55       ` Sebastian Hetze
     [not found]       ` <20100321145548.CC027A0015@mail.linux-ag.de>
2010-03-21 15:17         ` Avi Kivity
2010-03-21 15:47           ` Sebastian Hetze
2010-03-22 12:51           ` Sebastian Hetze
2010-03-23 21:18             ` Marcelo Tosatti
2010-03-30  8:27               ` Sebastian Hetze
     [not found]               ` <20100330082743.49A113030135@mail.linux-ag.de>
2010-04-05 21:24                 ` Sebastian Hetze [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=20100405212450.CEE7F30301D3@mail.linux-ag.de \
    --to=s.hetze@linux-ag.com \
    --cc=avi@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=mtosatti@redhat.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.