During reset the aio_poll() function is called at least amount_of_disks^2 times:
for_each disk
virtio_blk_reset()
bdrv_drain_all()
for_each disk
aio_poll()
For example, startup with 1000 disks takes over 13 minutes.
Patch 1/2 removes inner loop by using bdrv_drain() instead of bdrv_drain_all().
bdrv_drain() works on one disk at time.
Since bdrv_drain_all() is still called in other places, patch 2/2 optimizes
it for cases, where there are more disks than iothreads.
Thanks.
Alexander Yarygin (2):
block-backend: Introduce blk_drain() and replace blk_drain_all()
block: Let bdrv_drain_all() to call aio_poll() for each AioContext
block/block-backend.c | 5 +++++
block/io.c | 42 ++++++++++++++++++++++++++----------------
hw/block/virtio-blk.c | 2 +-
include/sysemu/block-backend.h | 1 +
4 files changed, 33 insertions(+), 17 deletions(-)
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1.9.1
