From: Christoph Hellwig <hch@infradead.org>
To: Antoine Martin <antoine@nagafix.co.uk>
Cc: Stefan Hajnoczi <stefanha@gmail.com>, Avi Kivity <avi@redhat.com>,
Michael Tokarev <mjt@tls.msk.ru>,
Christoph Hellwig <hch@infradead.org>,
kvm@vger.kernel.org
Subject: Re: raw disks no longer work in latest kvm (kvm-88 was fine)
Date: Sat, 29 May 2010 06:34:17 -0400 [thread overview]
Message-ID: <20100529103417.GA16311@infradead.org> (raw)
In-Reply-To: <4C00E1A3.50109@nagafix.co.uk>
On Sat, May 29, 2010 at 04:42:59PM +0700, Antoine Martin wrote:
> Can someone explain the aio options?
> All I can find is this:
> # qemu-system-x86_64 -h | grep -i aio
> [,addr=A][,id=name][,aio=threads|native]
> I assume it means the aio=threads emulates the kernel's aio with
> separate threads? And is therefore likely to be slower, right?
> Is there a reason why aio=native is not the default? Shouldn't
> aio=threads be the fallback?
The kernel AIO support is unfortunately not a very generic API.
It only supports O_DIRECT I/O (cache=none for qemu), and if used on
a filesystems it might still block if we need to perform block
allocations. We could probably make it the default for block devices,
but I'm not a big fan of these kind of conditional defaults.
next prev parent reply other threads:[~2010-05-29 10:34 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-06 20:48 raw disks no longer work in latest kvm (kvm-88 was fine) Antoine Martin
2010-03-06 21:28 ` Michael Tokarev
2010-03-07 4:14 ` Antoine Martin
2010-03-07 9:32 ` Michael Tokarev
2010-03-07 10:00 ` Christoph Hellwig
2010-03-07 13:12 ` Antoine Martin
2010-03-07 13:52 ` Antoine Martin
2010-03-07 15:15 ` Michael Tokarev
2010-03-07 17:11 ` Antoine Martin
2010-03-07 17:18 ` Avi Kivity
2010-03-07 17:21 ` Christoph Hellwig
2010-03-07 17:30 ` Avi Kivity
2010-03-07 17:34 ` Christoph Hellwig
2010-03-07 18:43 ` raw disks no longer work in latest kvm (kvm-88 was fine) [SOLVED] Antoine Martin
2010-03-07 18:55 ` Avi Kivity
2010-03-07 18:01 ` raw disks no longer work in latest kvm (kvm-88 was fine) Antoine Martin
2010-03-07 18:47 ` Avi Kivity
2010-03-07 19:07 ` Antoine Martin
2010-03-07 19:10 ` Avi Kivity
2010-03-07 19:13 ` Antoine Martin
2010-03-07 19:17 ` Avi Kivity
2010-03-07 19:25 ` Antoine Martin
2010-03-07 19:35 ` Avi Kivity
2010-03-13 9:51 ` Antoine Martin
2010-03-14 7:34 ` Avi Kivity
2010-04-08 22:00 ` Antoine Martin
2010-05-22 10:44 ` Antoine Martin
2010-05-22 11:17 ` Michael Tokarev
2010-05-22 11:35 ` Antoine Martin
2010-05-23 8:53 ` Antoine Martin
2010-05-23 11:57 ` Avi Kivity
2010-05-23 14:07 ` Antoine Martin
2010-05-23 14:18 ` Avi Kivity
2010-05-23 14:43 ` Antoine Martin
2010-05-23 14:53 ` Antoine Martin
2010-05-23 14:56 ` Avi Kivity
2010-05-23 15:06 ` Antoine Martin
2010-05-23 15:12 ` Avi Kivity
2010-05-23 16:18 ` Antoine Martin
2010-05-23 17:47 ` Stefan Hajnoczi
2010-05-29 9:42 ` Antoine Martin
2010-05-29 9:55 ` Stefan Hajnoczi
2010-05-29 10:34 ` Christoph Hellwig
2010-05-29 11:06 ` Stefan Hajnoczi
2010-05-29 10:34 ` Christoph Hellwig [this message]
2010-03-07 19:09 ` Asdo
2010-03-07 19:11 ` Antoine Martin
2010-03-07 19:12 ` Avi Kivity
2010-03-07 16:21 ` Avi Kivity
2010-03-08 16:45 ` Anthony Liguori
2010-03-07 9:36 ` Gleb Natapov
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