| Message ID | 1331564005-31070-1-git-send-email-zwu.kernel@gmail.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Mar 12, 2012 at 11:05 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > Il 12/03/2012 15:53, zwu.kernel@gmail.com ha scritto: >> - qemu_aio_flush(); >> + QTAILQ_FOREACH(bs, &bdrv_states, list) { >> + do { >> + qemu_co_queue_restart_all(&bs->throttled_reqs); >> + qemu_aio_flush(); >> + } while (!qemu_co_queue_empty(&bs->throttled_reqs)); >> + } > > Even this is not enough. Block device 2 could start a throttled request I think that this should be allowed here. It does not affect the final result. All throttled requests for all disks are drained. > on block device 1. I'm sending a related series, I'll include yours in > mine. > > Paolo
Il 12/03/2012 16:25, Zhi Yong Wu ha scritto: > > > - qemu_aio_flush(); > > > + QTAILQ_FOREACH(bs, &bdrv_states, list) { > > > + do { > > > + qemu_co_queue_restart_all(&bs->throttled_reqs); > > > + qemu_aio_flush(); > > > + } while (!qemu_co_queue_empty(&bs->throttled_reqs)); > > > + } > > > > Even this is not enough. Block device 2 could start a throttled request > > on block device 1. > > I think that this should be allowed here. It does not affect the final > result. All throttled requests for all disks are drained. Unfortunately, that depends on the order of block devices. It needs to be something like this: do { qemu_aio_flush(); busy = false; QTAILQ_FOREACH(bs, &bdrv_states, list) { if (!qemu_co_queue_empty(&bs->throttled_reqs)) { qemu_co_queue_restart_all(&bs->throttled_reqs); busy = true; } } } while (busy); This means that bdrv_drain() cannot be implemented. The device models can "drain themselves", but for example monitor commands must still rely on bdrv_drain_all(). Paolo
diff --git a/block.c b/block.c index 52ffe14..b3cbcc3 100644 --- a/block.c +++ b/block.c @@ -853,6 +853,20 @@ void bdrv_close_all(void) } } +/** + * Complete all pending requests for a block device + */ +void bdrv_drain(BlockDriverState *bs) +{ + do { + qemu_co_queue_restart_all(&bs->throttled_reqs); + qemu_aio_flush(); + } while (!qemu_co_queue_empty(&bs->throttled_reqs)); + + assert(QLIST_EMPTY(&bs->tracked_requests)); + assert(qemu_co_queue_empty(&bs->throttled_reqs)); +} + /* * Wait for pending requests to complete across all BlockDriverStates * @@ -863,7 +877,12 @@ void bdrv_drain_all(void) { BlockDriverState *bs; - qemu_aio_flush(); + QTAILQ_FOREACH(bs, &bdrv_states, list) { + do { + qemu_co_queue_restart_all(&bs->throttled_reqs); + qemu_aio_flush(); + } while (!qemu_co_queue_empty(&bs->throttled_reqs)); + } /* If requests are still pending there is a bug somewhere */ QTAILQ_FOREACH(bs, &bdrv_states, list) { diff --git a/block_int.h b/block_int.h index b460c36..c624399 100644 --- a/block_int.h +++ b/block_int.h @@ -318,6 +318,7 @@ void qemu_aio_release(void *p); void bdrv_set_io_limits(BlockDriverState *bs, BlockIOLimit *io_limits); +void bdrv_drain(BlockDriverState *bs); #ifdef _WIN32 int is_windows_drive(const char *filename);