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From: Paolo Bonzini <pbonzini@redhat.com>
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>
Subject: Re: [Qemu-devel] [PATCH v2] xen_disk: support "direct-io-safe" backend option
Date: Fri, 28 Jun 2013 18:26:15 +0200	[thread overview]
Message-ID: <51CDB927.80901@redhat.com> (raw)
In-Reply-To: <624B402D40D846D55A77B826@nimrod.local>

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

WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
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>
Subject: Re: [PATCH v2] xen_disk: support "direct-io-safe" backend option
Date: Fri, 28 Jun 2013 18:26:15 +0200	[thread overview]
Message-ID: <51CDB927.80901@redhat.com> (raw)
In-Reply-To: <624B402D40D846D55A77B826@nimrod.local>

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

  reply	other threads:[~2013-06-28 16:26 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-27 18:16 [Qemu-devel] [PATCH v2] xen_disk: support "direct-io-safe" backend option Stefano Stabellini
2013-06-27 18:16 ` Stefano Stabellini
2013-06-28  7:56 ` [Qemu-devel] " Paolo Bonzini
2013-06-28  7:56   ` Paolo Bonzini
2013-06-28 10:54   ` [Qemu-devel] " Ian Jackson
2013-06-28 10:54     ` Ian Jackson
2013-06-28 10:57   ` [Qemu-devel] " Stefano Stabellini
2013-06-28 10:57     ` Stefano Stabellini
2013-06-28  8:48 ` [Qemu-devel] " Alex Bligh
2013-06-28  8:48   ` Alex Bligh
2013-06-28 10:44   ` [Qemu-devel] " Ian Jackson
2013-06-28 10:44     ` Ian Jackson
2013-06-28 16:17     ` [Qemu-devel] " Alex Bligh
2013-06-28 16:17       ` Alex Bligh
2013-06-28 16:26       ` Paolo Bonzini [this message]
2013-06-28 16:26         ` Paolo Bonzini
2013-06-28 10:56   ` [Qemu-devel] " Stefano Stabellini
2013-06-28 10:56     ` Stefano Stabellini
2013-06-28 16:16 ` [Qemu-devel] " Stefano Stabellini
2013-06-28 16:51   ` George Dunlap

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