From: Avi Kivity <avi@redhat.com>
To: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Cc: kvm <kvm@vger.kernel.org>
Subject: Re: windows PIO question
Date: Sun, 05 Feb 2012 17:10:55 +0200 [thread overview]
Message-ID: <4F2E9BFF.1050700@redhat.com> (raw)
In-Reply-To: <20120202211630.GA4719@nik-comp.lan>
On 02/02/2012 11:16 PM, Nikola Ciprich wrote:
> Hello everybody,
>
> I'm a bit confused regarding windows guests and PIO.. some time ago, I was trying
> to find out, why one of my windows guests was running terribly slow.
> After checking the trace-cmd output, Avi stated that windows were using PIO instead
> of DMA, after changing that, windows indeed got a lot faster. I didn't check traces
> after that, but I'm now testing host with two windows 2003 guests, and checking the
> trac-cmd output, I see a lot of kvm_pio calls.
> While windows don't seem to be running particularly slow, they're not especially
> fast either, and I'm wandering whether this could be related. But checking IDE
> bus in guests, they seem to be using DMA which confuses me...
> so my questions is, what are the kvm_pio operations I see in traces, and how can
> I tell what is OK and what is wrong, regarding disks DMA/PIO?
> If somebody could shed some light on this for me, I'd be very grateful...
Not all PIO operations are DMA. Provide a trace and we can look.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-02-05 15:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-02 21:16 windows PIO question Nikola Ciprich
2012-02-05 15:10 ` Avi Kivity [this message]
2012-02-05 21:01 ` Nikola Ciprich
2012-02-06 9:50 ` Avi Kivity
2012-02-07 8:25 ` Nikola Ciprich
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