From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 27 Aug 2018 12:10:23 -0400 From: Konrad Rzeszutek Wilk To: Juergen Gross Cc: Roger Pau =?iso-8859-1?Q?Monn=E9?= , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, axboe@kernel.dk, boris.ostrovsky@oracle.com Subject: Re: [PATCH v3 0/5] xen/blk: persistent grant rework Message-ID: <20180827161023.GV10467@char.us.oracle.com> References: <20180813140114.20126-1-jgross@suse.com> <20180817155909.4cwiy6bhhgiala5m@mac> <8aaf02b1-999d-81fc-2732-ed556b959a8a@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <8aaf02b1-999d-81fc-2732-ed556b959a8a@suse.com> List-ID: On Fri, Aug 24, 2018 at 03:52:23PM +0200, Juergen Gross wrote: > On 17/08/18 17:59, Roger Pau Monn=E9 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 relat= ed > >> to persistent grants in some configurations: domains with multiple > >> block devices making use of persistent grants might suffer from a la= ck > >> of grants if each of the block devices experienced a high I/O load a= t > >> 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 gra= nts > >> not in use by blkback any more and to remove such grants. > >> > >> The last 3 patches are small cleanups of blkfront and blkback driver= s. > >> > >> V3: > >> - patch 1: make timeout parameter static > >=20 > > Konrad if you are OK with this series, could you please send a pull > > request to Jens? >=20 > Ping? Yes, let me do that now. >=20 >=20 > Juergen