From: Samuel Thibault <samuel.thibault@ens-lyon.org>
To: Gleb Natapov <gleb@kernel.org>
Cc: Jan Kiszka <jan.kiszka@web.de>, kvm@vger.kernel.org, pbonzini@redhat.com
Subject: Re: nested KVM slower than QEMU with gnumach guest kernel
Date: Mon, 17 Nov 2014 10:37:28 +0100 [thread overview]
Message-ID: <20141117093728.GA3953@type.bordeaux.inria.fr> (raw)
In-Reply-To: <20141117092122.GF26187@minantech.com>
Gleb Natapov, le Mon 17 Nov 2014 11:21:22 +0200, a écrit :
> On Mon, Nov 17, 2014 at 10:10:25AM +0100, Samuel Thibault wrote:
> > Jan Kiszka, le Mon 17 Nov 2014 10:04:37 +0100, a écrit :
> > > On 2014-11-17 10:03, Samuel Thibault wrote:
> > > > Gleb Natapov, le Mon 17 Nov 2014 10:58:45 +0200, a écrit :
> > > >> Do you know how gnumach timekeeping works? Does it have a timer that fires each 1ms?
> > > >> Which clock device is it using?
> > > >
> > > > It uses the PIT every 10ms, in square mode
> > > > (PIT_C0|PIT_SQUAREMODE|PIT_READMODE = 0x36).
> > >
> > > Wow... how retro. That feature might be unsupported - does user space
> > > irqchip work better?
> >
> > I had indeed tried giving -machine kernel_irqchip=off to the L2 kvm,
> > with the same bad performance and external_interrupt in the trace.
> >
> They are always be in the trace, but do you see them each ms or each 10ms
> with user space irqchip?
The external interupts are every 1 *microsecond, not millisecond. With
irqchip=off or not.
Samuel
next prev parent reply other threads:[~2014-11-17 9:37 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-11 18:55 nested KVM slower than QEMU with gnumach guest kernel Samuel Thibault
2014-11-11 23:42 ` Jan Kiszka
2014-11-16 22:18 ` Samuel Thibault
2014-11-17 6:28 ` Jan Kiszka
2014-11-17 8:50 ` Samuel Thibault
2014-11-24 0:42 ` Samuel Thibault
2014-12-15 0:09 ` Samuel Thibault
2014-12-15 9:41 ` Paolo Bonzini
2014-11-17 8:58 ` Gleb Natapov
2014-11-17 9:03 ` Samuel Thibault
2014-11-17 9:04 ` Jan Kiszka
2014-11-17 9:10 ` Samuel Thibault
2014-11-17 9:21 ` Gleb Natapov
2014-11-17 9:37 ` Samuel Thibault [this message]
2014-11-17 9:38 ` Samuel Thibault
2014-11-23 21:50 ` Samuel Thibault
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=20141117093728.GA3953@type.bordeaux.inria.fr \
--to=samuel.thibault@ens-lyon.org \
--cc=gleb@kernel.org \
--cc=jan.kiszka@web.de \
--cc=kvm@vger.kernel.org \
--cc=pbonzini@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.