linux-kernel - Re: [PATCH v3 0/5] xen/blk: persistent grant rework

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Message-ID: <20180827161023.GV10467@char.us.oracle.com>
Date:   Mon, 27 Aug 2018 12:10:23 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Juergen Gross <jgross@...e.com>
Cc:     Roger Pau Monné <roger.pau@...rix.com>,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        linux-block@...r.kernel.org, axboe@...nel.dk,
        boris.ostrovsky@...cle.com
Subject: Re: [PATCH v3 0/5] xen/blk: persistent grant rework

On Fri, Aug 24, 2018 at 03:52:23PM +0200, Juergen Gross wrote:
> On 17/08/18 17:59, Roger Pau Monné wrote:
> > On Mon, Aug 13, 2018 at 04:01:09PM +0200, Juergen Gross wrote:
> >> Persistent grants are used in the Xen's blkfront/blkback drivers to
> >> avoid mapping/unmapping of I/O buffers in the backend for each I/O.
> >>
> >> While this speeds up processing quite a bit there are problems related
> >> to persistent grants in some configurations: domains with multiple
> >> block devices making use of persistent grants might suffer from a lack
> >> of grants if each of the block devices experienced a high I/O load at
> >> some time. This is due to the number of persistent grants per device
> >> only to be limited by a rather high maximum value, but never being
> >> released even in case of longer times without any I/O.
> >>
> >> This series modifies xen-blkback to unmap any domU page mapped via a
> >> persistent grant after a timeout (default: 60 seconds). The timeout
> >> is set to its default value again when a persistent grant has been
> >> used for an I/O.
> >>
> >> xen-blkfront is modified to scan every 10 seconds for persistent grants
> >> not in use by blkback any more and to remove such grants.
> >>
> >> The last 3 patches are small cleanups of blkfront and blkback drivers.
> >>
> >> V3:
> >> - patch 1: make timeout parameter static
> > 
> > Konrad if you are OK with this series, could you please send a pull
> > request to Jens?
> 
> Ping?

Yes, let me do that now.
> 
> 
> Juergen