Re: [Qemu-devel] [PATCH v4 1/3] block: ignore flush requests when storage is clean

2016-06-29 Thread Stefan Hajnoczi
On Wed, Jun 29, 2016 at 09:12:41AM +0800, Fam Zheng wrote: > On Tue, 06/28 12:10, Denis V. Lunev wrote: > > On 06/28/2016 04:27 AM, Fam Zheng wrote: > > > On Mon, 06/27 17:47, Denis V. Lunev wrote: > > > > From: Evgeny Yakovlev > > > > > > > > Some guests (win2008 server

Re: [Qemu-devel] [PATCH v4 1/3] block: ignore flush requests when storage is clean

2016-06-29 Thread Denis V. Lunev
On 06/29/2016 04:12 AM, Fam Zheng wrote: On Tue, 06/28 12:10, Denis V. Lunev wrote: On 06/28/2016 04:27 AM, Fam Zheng wrote: On Mon, 06/27 17:47, Denis V. Lunev wrote: From: Evgeny Yakovlev Some guests (win2008 server for example) do a lot of unnecessary flushing

Re: [Qemu-devel] [PATCH v4 1/3] block: ignore flush requests when storage is clean

2016-06-28 Thread Fam Zheng
On Tue, 06/28 12:10, Denis V. Lunev wrote: > On 06/28/2016 04:27 AM, Fam Zheng wrote: > > On Mon, 06/27 17:47, Denis V. Lunev wrote: > > > From: Evgeny Yakovlev > > > > > > Some guests (win2008 server for example) do a lot of unnecessary > > > flushing when underlying

Re: [Qemu-devel] [PATCH v4 1/3] block: ignore flush requests when storage is clean

2016-06-28 Thread Denis V. Lunev
On 06/28/2016 04:27 AM, Fam Zheng wrote: On Mon, 06/27 17:47, Denis V. Lunev wrote: From: Evgeny Yakovlev Some guests (win2008 server for example) do a lot of unnecessary flushing when underlying media has not changed. This adds additional overhead on host when

Re: [Qemu-devel] [PATCH v4 1/3] block: ignore flush requests when storage is clean

2016-06-27 Thread Fam Zheng
On Mon, 06/27 17:47, Denis V. Lunev wrote: > From: Evgeny Yakovlev > > Some guests (win2008 server for example) do a lot of unnecessary > flushing when underlying media has not changed. This adds additional > overhead on host when calling fsync/fdatasync. > > This

[Qemu-devel] [PATCH v4 1/3] block: ignore flush requests when storage is clean

2016-06-27 Thread Denis V. Lunev
From: Evgeny Yakovlev Some guests (win2008 server for example) do a lot of unnecessary flushing when underlying media has not changed. This adds additional overhead on host when calling fsync/fdatasync. This change introduces a dirty flag in BlockDriverState which is