Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Anthony Liguori
On 05/20/2010 08:49 AM, Jes Sorensen wrote: On 05/20/10 15:40, Anthony Liguori wrote: On 05/20/2010 08:36 AM, Jes Sorensen wrote: And I strongly suspect that such a blanket change would be wrong but that a more targeted change like making cache=none default for physical devices would

Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Stefan Hajnoczi
On Thu, May 20, 2010 at 2:49 PM, Jes Sorensen wrote: > On 05/20/10 15:40, Anthony Liguori wrote: >> On 05/20/2010 08:36 AM, Jes Sorensen wrote: And I strongly suspect that such a blanket change would be wrong but that a more targeted change like making cache=none default for physical >>>

Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Jes Sorensen
On 05/20/10 15:40, Anthony Liguori wrote: > On 05/20/2010 08:36 AM, Jes Sorensen wrote: >>> And I strongly suspect that such a blanket change would be wrong but >>> that a more targeted change like making cache=none default for physical >>> devices would satisfy mostly everyone. >>> >> Is the

Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Anthony Liguori
On 05/20/2010 08:36 AM, Jes Sorensen wrote: On 05/20/10 14:30, Anthony Liguori wrote: On 05/20/2010 04:32 AM, jes.soren...@redhat.com wrote: Therefore, here is a patch that does two things: - default to "nocache" - in case of failure with nocache, retry with "write-back"

Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Jes Sorensen
On 05/20/10 14:30, Anthony Liguori wrote: > On 05/20/2010 04:32 AM, jes.soren...@redhat.com wrote: >> Therefore, here is a patch that does two things: >> - default to "nocache" >> - in case of failure with nocache, retry with "write-back" >> > > This sort of change requires performance dat

Re: [Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Anthony Liguori
On 05/20/2010 04:32 AM, jes.soren...@redhat.com wrote: From: Jes Sorensen We seem to get into the discussion of what is the correct default setting disk images in QEMU. The libvirt team is reluctant to change specified for newly created images without the default setting matching it, and everybo

[Qemu-devel] [PATCH] QEMU: change default disk cache behavior

2010-05-20 Thread Jes . Sorensen
From: Jes Sorensen We seem to get into the discussion of what is the correct default setting disk images in QEMU. The libvirt team is reluctant to change specified for newly created images without the default setting matching it, and everybody seems to agree that the current setting of WT is the