| Message ID | 20180813140114.20126-1-jgross@suse.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | xen/blk: persistent grant rework | expand |
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.
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? Juergen
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