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[Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased. |
Date: |
Fri, 24 Dec 2010 11:44:17 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Dec 24, 2010 at 12:18:15PM +0900, Yoshiaki Tamura wrote:
> virtio save/load is currently sending last_avail_idx, but inuse isn't.
> This causes inconsistent state when using Kemari which replays
> outstanding requests on the secondary. By letting last_avail_idx to
> be updated after inuse is decreased, it would be possible to replay
> the outstanding requests. Noth that live migration shouldn't be
> affected because it waits until flushing all requests. Also in
> conjunction with event-tap, requests inversion should be avoided.
>
> Signed-off-by: Yoshiaki Tamura <address@hidden>
I think I understood the request inversion. My question now is,
event-tap transfers inuse events as well, wont the same
request be repeated twice?
> ---
> hw/virtio.c | 8 +++++++-
> 1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/hw/virtio.c b/hw/virtio.c
> index 07dbf86..f915c46 100644
> --- a/hw/virtio.c
> +++ b/hw/virtio.c
> @@ -72,7 +72,7 @@ struct VirtQueue
> VRing vring;
> target_phys_addr_t pa;
> uint16_t last_avail_idx;
> - int inuse;
> + uint16_t inuse;
> uint16_t vector;
> void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);
> VirtIODevice *vdev;
> @@ -671,6 +671,7 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> qemu_put_be32(f, vdev->vq[i].vring.num);
> qemu_put_be64(f, vdev->vq[i].pa);
> qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
> + qemu_put_be16s(f, &vdev->vq[i].inuse);
> if (vdev->binding->save_queue)
> vdev->binding->save_queue(vdev->binding_opaque, i, f);
> }
> @@ -710,6 +711,11 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
> vdev->vq[i].vring.num = qemu_get_be32(f);
> vdev->vq[i].pa = qemu_get_be64(f);
> qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
> + qemu_get_be16s(f, &vdev->vq[i].inuse);
> +
> + /* revert last_avail_idx if there are outstanding emulation. */
if there are outstanding emulation -> if requests
are outstanding in event-tap?
> + vdev->vq[i].last_avail_idx -= vdev->vq[i].inuse;
> + vdev->vq[i].inuse = 0;
>
I don't understand it, if this is all we do we can equivalently
decrement on the sender side and avoid breaking migration compatibility?
> if (vdev->vq[i].pa) {
> uint16_t nheads;
> --
> 1.7.1.2
- [Qemu-devel] [PATCH 02/19] Introduce read() to FdMigrationState., (continued)
- [Qemu-devel] [PATCH 02/19] Introduce read() to FdMigrationState., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 10/19] Call init handler of event-tap at main() in vl.c., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 04/19] qemu-char: export socket_set_nodelay()., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 01/19] Make QEMUFile buf expandable, and introduce qemu_realloc_buffer() and qemu_clear_buffer()., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 12/19] Insert event_tap_mmio() to cpu_physical_memory_rw() in exec.c., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 05/19] vl.c: add deleted flag for deleting the handler., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 11/19] ioport: insert event_tap_ioport() to ioport_write()., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 07/19] Introduce fault tolerant VM transaction QEMUFile and ft_mode., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 18/19] Introduce -k option to enable FT migration mode (Kemari)., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased., Yoshiaki Tamura, 2010/12/23
- [Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased.,
Michael S. Tsirkin <=
- [Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased., Yoshiaki Tamura, 2010/12/24
- [Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased., Michael S. Tsirkin, 2010/12/24
- [Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased., Yoshiaki Tamura, 2010/12/24
- [Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased., Michael S. Tsirkin, 2010/12/24
- Re: [Qemu-devel] Re: [PATCH 06/19] virtio: update last_avail_idx when inuse is decreased., Yoshiaki Tamura, 2010/12/24
[Qemu-devel] [PATCH 19/19] migration: add a parser to accept FT migration incoming mode., Yoshiaki Tamura, 2010/12/23
[Qemu-devel] [PATCH 14/19] block: insert event-tap to bdrv_aio_writev() and bdrv_aio_flush()., Yoshiaki Tamura, 2010/12/23
[Qemu-devel] [PATCH 16/19] migration: introduce migrate_ft_trans_{put, get}_ready(), and modify migrate_fd_put_ready() when ft_mode is on., Yoshiaki Tamura, 2010/12/23
[Qemu-devel] [PATCH 08/19] savevm: introduce util functions to control ft_trans_file from savevm layer., Yoshiaki Tamura, 2010/12/23
[Qemu-devel] [PATCH 17/19] migration-tcp: modify tcp_accept_incoming_migration() to handle ft_mode, and add a hack not to close fd when ft_mode is enabled., Yoshiaki Tamura, 2010/12/23