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Date: Fri, 28 Jun 2013 18:26:15 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v2] xen_disk: support "direct-io-safe"
 backend option
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To: Alex Bligh <alex@alex.org.uk>
Cc: xen-devel@lists.xensource.com, Ian Jackson <Ian.Jackson@eu.citrix.com>, qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Il 28/06/2013 18:17, Alex Bligh ha scritto:
> 
> But as Stefano says:
> 
> --On 28 June 2013 11:56:29 +0100 Stefano Stabellini
> <stefano.stabellini@eu.citrix.com> wrote:
> 
>> This is PV only, at least for the moment: emulated disks always use
>> writeback caching.
>> From the performance point of view, making this change for IDE disks is
>> not very important (because IDE is slow anyway).
> 
> ... perhaps 'who cares'.

There are plenty of emulated devices that are not that slow, though
perhaps Xen management does not support them: AHCI, MegaSAS, VMware
pvscsi, and of course virtio-{blk,scsi}...

Paolo