Marcelo Tosatti wrote:
On Tue, Nov 30, 2010 at 06:28:55PM +0900, Yoshiaki Tamura wrote:
2010/11/30 Marcelo Tosatti<mtosatti@xxxxxxxxxx>:
On Thu, Nov 25, 2010 at 03:06:48PM +0900, Yoshiaki Tamura wrote:
event-tap controls when to start FT transaction, and provides proxy
functions to called from net/block devices. While FT transaction, it
queues up net/block requests, and flush them when the transaction gets
completed.
Signed-off-by: Yoshiaki Tamura<tamura.yoshiaki@xxxxxxxxxxxxx>
Signed-off-by: OHMURA Kei<ohmura.kei@xxxxxxxxxxxxx>
+static void event_tap_alloc_blk_req(EventTapBlkReq *blk_req,
+ BlockDriverState *bs, BlockRequest *reqs,
+ int num_reqs, BlockDriverCompletionFunc *cb,
+ void *opaque, bool is_multiwrite)
+{
+ int i;
+
+ blk_req->num_reqs = num_reqs;
+ blk_req->num_cbs = num_reqs;
+ blk_req->device_name = qemu_strdup(bs->device_name);
+ blk_req->is_multiwrite = is_multiwrite;
+
+ for (i = 0; i< num_reqs; i++) {
+ blk_req->reqs[i].sector = reqs[i].sector;
+ blk_req->reqs[i].nb_sectors = reqs[i].nb_sectors;
+ blk_req->reqs[i].qiov = reqs[i].qiov;
+ blk_req->reqs[i].cb = cb;
+ blk_req->reqs[i].opaque = opaque;
+ blk_req->cb[i] = reqs[i].cb;
+ blk_req->opaque[i] = reqs[i].opaque;
+ }
+}
bdrv_aio_flush should also be logged, so that guest initiated flush is
respected on replay.
In the current implementation w/o flush logging, there might be
order inversion after replay?
Yoshi
Yes, since a vcpu is allowed to continue after synchronization is
scheduled via a bh. For virtio-blk, for example:
1) bdrv_aio_write, event queued.
2) bdrv_aio_flush
3) bdrv_aio_write, event queued.
On replay, there is no flush between the two writes.
Why can't synchronization be done from event-tap itself, synchronously,
to avoid this kind of problem?
Thanks. I would fix it.
The way you hook synchronization into savevm seems unclean. Perhaps
better separation between standard savevm path and FT savevm would make
it cleaner.
I think you're mentioning about the changes in migration.c?
Yoshi
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