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mirror: fix request throttling in drive-mirror 

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 <den@openvz.org>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1466598927-5990-1-git-send-email-den@openvz.org
CC: Jeff Cody <jcody@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Max Reitz <mreitz@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
(cherry picked from commit e648dc95c28fbca12e67be26a1fc4b9a0676c3fe)
This commit is contained in:
Denis V. Lunev 2016-06-22 15:35:27 +03:00 committed by Jeff Cody
parent 4b5004d9fc
commit cf56a3c632
1 changed files with 6 additions and 1 deletions
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7
block/mirror.c
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@ -407,6 +407,11 @@ 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:
@ -695,7 +700,7 @@ static void coroutine_fn mirror_run(void *opaque)
delta = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - s->last_pause_ns;
if (delta < 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);