There are 2 deficiencies here:
- mirror_iteration could start several requests inside. Thus we could
simply have more in_flight requests than MAX_IN_FLIGHT.
- keeping this in mind throttling in mirror_run which is checking
s->in_flight == MAX_IN_FLIGHT is wrong.
The patch adds the check and throttling into mirror_iteration and fixes
the check in mirror_run() to be sure.
Signed-off-by: Denis V. Lunev <d...@openvz.org>
CC: Jeff Cody <jc...@redhat.com>
CC: Kevin Wolf <kw...@redhat.com>
CC: Max Reitz <mre...@redhat.com>
---
block/mirror.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/block/mirror.c b/block/mirror.c
index a04ed9c..e881ef6 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -399,6 +399,11 @@ static uint64_t coroutine_fn
mirror_iteration(MirrorBlockJob *s)
}
}
+ while (s->in_flight >= MAX_IN_FLIGHT) {
+ trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
+ mirror_wait_for_io(s);
+ }
+
mirror_clip_sectors(s, sector_num, &io_sectors);
switch (mirror_method) {
case MIRROR_METHOD_COPY:
@@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque)
*/
if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns <
SLICE_TIME &&
s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
- if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 ||
+ if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 ||
(cnt == 0 && s->in_flight > 0)) {
trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt);
mirror_wait_for_io(s);
--
2.1.4
