Re: [PATCH 3/3] block/nbd: nbd_co_reconnect_loop(): don't sleep if drained
23.07.2020 21:55, Eric Blake wrote: On 7/20/20 4:00 AM, Vladimir Sementsov-Ogievskiy wrote: We try to go to wakeable sleep, so that, if drain begins it will break the sleep. But what if nbd_client_co_drain_begin() already called and s->drained is already true? We'll go to sleep, and drain will have to wait for the whole timeout. Let's improve it. Signed-off-by: Vladimir Sementsov-Ogievskiy --- block/nbd.c | 11 ++- 1 file changed, 6 insertions(+), 5 deletions(-) How frequently did you hit this case? At any rate, the optimization looks sane, and I'm happy to include it in 5.1. I don't remember. Probably once? And, as I said in cover letter, it even was not master branch but some my experiment.. -- Best regards, Vladimir
Re: [PATCH 3/3] block/nbd: nbd_co_reconnect_loop(): don't sleep if drained
On 7/20/20 4:00 AM, Vladimir Sementsov-Ogievskiy wrote: We try to go to wakeable sleep, so that, if drain begins it will break the sleep. But what if nbd_client_co_drain_begin() already called and s->drained is already true? We'll go to sleep, and drain will have to wait for the whole timeout. Let's improve it. Signed-off-by: Vladimir Sementsov-Ogievskiy --- block/nbd.c | 11 ++- 1 file changed, 6 insertions(+), 5 deletions(-) How frequently did you hit this case? At any rate, the optimization looks sane, and I'm happy to include it in 5.1. Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org
[PATCH 3/3] block/nbd: nbd_co_reconnect_loop(): don't sleep if drained
We try to go to wakeable sleep, so that, if drain begins it will break
the sleep. But what if nbd_client_co_drain_begin() already called and
s->drained is already true? We'll go to sleep, and drain will have to
wait for the whole timeout. Let's improve it.
Signed-off-by: Vladimir Sementsov-Ogievskiy
---
block/nbd.c | 11 ++-
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/block/nbd.c b/block/nbd.c
index 42146a26f7..d9cde30457 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -327,8 +327,6 @@ static coroutine_fn void nbd_co_reconnect_loop(BDRVNBDState
*s)
qemu_co_queue_restart_all(&s->free_sema);
}
-qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, timeout,
- &s->connection_co_sleep_ns_state);
if (s->drained) {
bdrv_dec_in_flight(s->bs);
s->wait_drained_end = true;
@@ -340,9 +338,12 @@ static coroutine_fn void
nbd_co_reconnect_loop(BDRVNBDState *s)
qemu_coroutine_yield();
}
bdrv_inc_in_flight(s->bs);
-}
-if (timeout < max_timeout) {
-timeout *= 2;
+} else {
+qemu_co_sleep_ns_wakeable(QEMU_CLOCK_REALTIME, timeout,
+ &s->connection_co_sleep_ns_state);
+if (timeout < max_timeout) {
+timeout *= 2;
+}
}
nbd_reconnect_attempt(s);
--
2.21.0
