From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@qumranet.com>
Cc: kvm-devel <kvm-devel@lists.sourceforge.net>,
linux-kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: kvm & dyntick
Date: Fri, 12 Jan 2007 11:19:31 +0100 [thread overview]
Message-ID: <20070112101931.GA11635@elte.hu> (raw)
In-Reply-To: <20070112062006.GA32714@elte.hu>
* Ingo Molnar <mingo@elte.hu> wrote:
> > dyntick-enabled guest:
> > - reduce the load on the host when the guest is idling
> > (currently an idle guest consumes a few percent cpu)
>
> yeah. KVM under -rt already works with dynticks enabled on both the
> host and the guest. (but it's more optimal to use a dedicated
> hypercall to set the next guest-interrupt)
using the dynticks code from the -rt kernel makes the overhead of an
idle guest go down by a factor of 10-15:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2556 mingo 15 0 598m 159m 157m R 1.5 8.0 0:26.20 qemu
( for this to work on my system i have added a 'hyper' clocksource
hypercall API for KVM guests to use - this is needed instead of the
running-to-slowly TSC. )
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
To: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Cc: kvm-devel
<kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>,
linux-kernel
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: kvm & dyntick
Date: Fri, 12 Jan 2007 11:19:31 +0100 [thread overview]
Message-ID: <20070112101931.GA11635@elte.hu> (raw)
In-Reply-To: <20070112062006.GA32714-X9Un+BFzKDI@public.gmane.org>
* Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org> wrote:
> > dyntick-enabled guest:
> > - reduce the load on the host when the guest is idling
> > (currently an idle guest consumes a few percent cpu)
>
> yeah. KVM under -rt already works with dynticks enabled on both the
> host and the guest. (but it's more optimal to use a dedicated
> hypercall to set the next guest-interrupt)
using the dynticks code from the -rt kernel makes the overhead of an
idle guest go down by a factor of 10-15:
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
2556 mingo 15 0 598m 159m 157m R 1.5 8.0 0:26.20 qemu
( for this to work on my system i have added a 'hyper' clocksource
hypercall API for KVM guests to use - this is needed instead of the
running-to-slowly TSC. )
Ingo
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys - and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
next prev parent reply other threads:[~2007-01-12 10:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-11 16:08 kvm & dyntick Avi Kivity
2007-01-11 16:08 ` Avi Kivity
2007-01-12 5:34 ` Rik van Riel
2007-01-12 5:34 ` Rik van Riel
2007-01-12 6:20 ` Ingo Molnar
2007-01-12 6:20 ` Ingo Molnar
2007-01-12 10:19 ` Ingo Molnar [this message]
2007-01-12 10:19 ` Ingo Molnar
2007-01-12 17:04 ` Avi Kivity
2007-01-12 17:04 ` Avi Kivity
2007-01-14 8:39 ` Ingo Molnar
2007-01-12 23:25 ` [kvm-devel] " Dor Laor
2007-01-12 23:39 ` Thomas Gleixner
2007-01-14 8:51 ` Ingo Molnar
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=20070112101931.GA11635@elte.hu \
--to=mingo@elte.hu \
--cc=avi@qumranet.com \
--cc=kvm-devel@lists.sourceforge.net \
--cc=linux-kernel@vger.kernel.org \
--cc=tglx@linutronix.de \
/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.