From: Gleb Natapov <gleb@kernel.org>
To: Samuel Thibault <samuel.thibault@ens-lyon.org>,
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 11:21:22 +0200 [thread overview]
Message-ID: <20141117092122.GF26187@minantech.com> (raw)
In-Reply-To: <20141117091025.GS3110@type.youpi.perso.aquilenet.fr>
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?
--
Gleb.
next prev parent reply other threads:[~2014-11-17 9:21 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 [this message]
2014-11-17 9:37 ` Samuel Thibault
2014-11-17 9:38 ` Samuel Thibault
2014-11-23 21:50 ` Samuel Thibault
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