From cf56a3c632d039d00e29dfe8676321d6d349190c Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Wed, 22 Jun 2016 15:35:27 +0300 Subject: [PATCH] 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 Reviewed-by: Max Reitz Message-id: 1466598927-5990-1-git-send-email-den@openvz.org CC: Jeff Cody CC: Kevin Wolf CC: Max Reitz Signed-off-by: Jeff Cody (cherry picked from commit e648dc95c28fbca12e67be26a1fc4b9a0676c3fe) --- block/mirror.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/block/mirror.c b/block/mirror.c index f78186d47b..836a5d0194 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -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);