From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 17 Aug 2018 17:59:09 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Juergen Gross CC: , , , , , Subject: Re: [PATCH v3 0/5] xen/blk: persistent grant rework Message-ID: <20180817155909.4cwiy6bhhgiala5m@mac> References: <20180813140114.20126-1-jgross@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" In-Reply-To: <20180813140114.20126-1-jgross@suse.com> Return-Path: roger.pau@citrix.com List-ID: 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? Thanks, Roger.