Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-12 Thread Fabiano Rosas
Peter Xu writes: > On Wed, Jun 12, 2024 at 07:15:19PM +0100, Daniel P. Berrangé wrote: >> IIUC, with the "fixed-ram" feature, the on-disk format of a saved VM >> should end up the same whether we're using traditional migration, or >> multifd migration. Use of multifd is simply an optimization

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-12 Thread Peter Xu
On Wed, Jun 12, 2024 at 07:15:19PM +0100, Daniel P. Berrangé wrote: > IIUC, with the "fixed-ram" feature, the on-disk format of a saved VM > should end up the same whether we're using traditional migration, or > multifd migration. Use of multifd is simply an optimization that lets > us write RAM

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-12 Thread Daniel P . Berrangé
On Wed, Jun 12, 2024 at 03:08:02PM -0300, Fabiano Rosas wrote: > Fabiano Rosas writes: > > > Peter Xu writes: > > > >> On Mon, Jun 10, 2024 at 02:45:53PM -0300, Fabiano Rosas wrote: > I looked into this and it's cumbersome: > > - We'd need to check migrate_direct_io() several times, once to

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-12 Thread Fabiano Rosas
Fabiano Rosas writes: > Peter Xu writes: > >> On Mon, Jun 10, 2024 at 02:45:53PM -0300, Fabiano Rosas wrote: >>> >> AIUI, the issue here that users are already allowed to specify in >>> >> libvirt the equivalent to direct-io and multifd independent of each >>> >> other (bypass-cache, parallel).

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-10 Thread Fabiano Rosas
Peter Xu writes: > On Mon, Jun 10, 2024 at 02:45:53PM -0300, Fabiano Rosas wrote: >> >> AIUI, the issue here that users are already allowed to specify in >> >> libvirt the equivalent to direct-io and multifd independent of each >> >> other (bypass-cache, parallel). To start requiring both

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-10 Thread Daniel P . Berrangé
On Mon, Jun 10, 2024 at 03:02:10PM -0400, Peter Xu wrote: > On Mon, Jun 10, 2024 at 02:45:53PM -0300, Fabiano Rosas wrote: > > >> AIUI, the issue here that users are already allowed to specify in > > >> libvirt the equivalent to direct-io and multifd independent of each > > >> other (bypass-cache,

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-10 Thread Peter Xu
On Mon, Jun 10, 2024 at 02:45:53PM -0300, Fabiano Rosas wrote: > >> AIUI, the issue here that users are already allowed to specify in > >> libvirt the equivalent to direct-io and multifd independent of each > >> other (bypass-cache, parallel). To start requiring both together now in > >> some

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-10 Thread Fabiano Rosas
Peter Xu writes: > On Fri, Jun 07, 2024 at 03:42:35PM -0300, Fabiano Rosas wrote: >> Peter Xu writes: >> >> > On Thu, May 23, 2024 at 04:05:48PM -0300, Fabiano Rosas wrote: >> >> We've recently added support for direct-io with multifd, which brings >> >> performance benefits, but creates a

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-10 Thread Peter Xu
On Fri, Jun 07, 2024 at 03:42:35PM -0300, Fabiano Rosas wrote: > Peter Xu writes: > > > On Thu, May 23, 2024 at 04:05:48PM -0300, Fabiano Rosas wrote: > >> We've recently added support for direct-io with multifd, which brings > >> performance benefits, but creates a non-uniform user interface by

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-07 Thread Fabiano Rosas
Peter Xu writes: > On Thu, May 23, 2024 at 04:05:48PM -0300, Fabiano Rosas wrote: >> We've recently added support for direct-io with multifd, which brings >> performance benefits, but creates a non-uniform user interface by >> coupling direct-io with the multifd capability. This means that users

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-07 Thread Jim Fehlig
On 6/7/24 12:42 PM, Fabiano Rosas wrote: Peter Xu writes: On Thu, May 23, 2024 at 04:05:48PM -0300, Fabiano Rosas wrote: We've recently added support for direct-io with multifd, which brings performance benefits, but creates a non-uniform user interface by coupling direct-io with the multifd

Re: [PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-06-04 Thread Peter Xu
On Thu, May 23, 2024 at 04:05:48PM -0300, Fabiano Rosas wrote: > We've recently added support for direct-io with multifd, which brings > performance benefits, but creates a non-uniform user interface by > coupling direct-io with the multifd capability. This means that users > cannot keep the

[PATCH v2 18/18] migration/ram: Add direct-io support to precopy file migration

2024-05-23 Thread Fabiano Rosas
We've recently added support for direct-io with multifd, which brings performance benefits, but creates a non-uniform user interface by coupling direct-io with the multifd capability. This means that users cannot keep the direct-io flag enabled while disabling multifd. Libvirt in particular