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    SubjectRe: [Xen-devel] [PATCH 3/3] xen/block: add multi-page ring support
    On Tue, Jun 09, 2015 at 10:21:27AM -0400, Konrad Rzeszutek Wilk wrote:
    > On Tue, Jun 09, 2015 at 04:07:33PM +0200, Roger Pau Monn? wrote:
    > > El 09/06/15 a les 15.39, Konrad Rzeszutek Wilk ha escrit:
    > > > On Tue, Jun 09, 2015 at 08:52:53AM +0000, Paul Durrant wrote:
    > > >>> -----Original Message-----
    > > >>> From: Bob Liu [mailto:bob.liu@oracle.com]
    > > >>> Sent: 09 June 2015 09:50
    > > >>> To: Bob Liu
    > > >>> Cc: xen-devel@lists.xen.org; David Vrabel; justing@spectralogic.com;
    > > >>> konrad.wilk@oracle.com; Roger Pau Monne; Paul Durrant; Julien Grall; linux-
    > > >>> kernel@vger.kernel.org
    > > >>> Subject: Re: [PATCH 3/3] xen/block: add multi-page ring support
    > > >>>
    > > >>>
    > > >>> On 06/03/2015 01:40 PM, Bob Liu wrote:
    > > >>>> Extend xen/block to support multi-page ring, so that more requests can be
    > > >>>> issued by using more than one pages as the request ring between blkfront
    > > >>>> and backend.
    > > >>>> As a result, the performance can get improved significantly.
    > > >>>>
    > > >>>> We got some impressive improvements on our highend iscsi storage cluster
    > > >>>> backend. If using 64 pages as the ring, the IOPS increased about 15 times
    > > >>>> for the throughput testing and above doubled for the latency testing.
    > > >>>>
    > > >>>> The reason was the limit on outstanding requests is 32 if use only one-page
    > > >>>> ring, but in our case the iscsi lun was spread across about 100 physical
    > > >>>> drives, 32 was really not enough to keep them busy.
    > > >>>>
    > > >>>> Changes in v2:
    > > >>>> - Rebased to 4.0-rc6.
    > > >>>> - Document on how multi-page ring feature working to linux io/blkif.h.
    > > >>>>
    > > >>>> Changes in v3:
    > > >>>> - Remove changes to linux io/blkif.h and follow the protocol defined
    > > >>>> in io/blkif.h of XEN tree.
    > > >>>> - Rebased to 4.1-rc3
    > > >>>>
    > > >>>> Changes in v4:
    > > >>>> - Turn to use 'ring-page-order' and 'max-ring-page-order'.
    > > >>>> - A few comments from Roger.
    > > >>>>
    > > >>>> Changes in v5:
    > > >>>> - Clarify with 4k granularity to comment
    > > >>>> - Address more comments from Roger
    > > >>>>
    > > >>>> Signed-off-by: Bob Liu <bob.liu@oracle.com>
    > > >>>
    > > >>> Also tested the windows PV driver which also works fine when multi-page
    > > >>> ring feature
    > > >>> was enabled in Linux backend.
    > > >>> http://www.xenproject.org/downloads/windows-pv-drivers.html
    > > >>>
    > > >>
    > > >> Great! Thanks for verifying that :-)
    > > >
    > > > Woot! Bob, could you repost the blkif.h patch for the Xen tree
    > > > pleas e and also mention the testing part in it please? I think this
    > > > was the only big 'what if?!' question holding this up.
    > > >
    > > >
    > > > Roger, I put them (patches) on devel/for-jens-4.2 on
    > > >
    > > > git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git
    > > >
    > > > I think these two patches:
    > > > drivers: xen-blkback: delay pending_req allocation to connect_ring
    > > > xen/block: add multi-page ring support
    > > >
    > > > are the only ones that haven't been Acked by you (or maybe they
    > > > have and I missed the Ack?)
    > >
    > > Hello,
    > >
    > > I was waiting to Ack those because the XenServer storage performance
    > > folks found out that these patches cause a performance regression on
    > > some of their tests. I'm adding them to the conversation so they can
    >
    > This is with multi-page enabled or with the patches but multi-page
    > disabled (baseline)?
    >
    > > provide more details about the issues they found, and whether we should
    > > hold pushing this patches or not.
    >
    > Or surely fix whatever is causing this.


    ping?


    > >
    > > Roger.
    > >
    >
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    > http://lists.xen.org/xen-devel
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