With a bdrv_co_write_zeroes method on a target BDS zeroes will not be placed into the wire. Thus the target could be very efficiently zeroed out. This is should be done with the largest chunk possible.
Signed-off-by: Denis V. Lunev <[email protected]> Reviewed-by: Vladimir Sementsov-Ogievskiy<[email protected]> CC: Stefan Hajnoczi <[email protected]> CC: Fam Zheng <[email protected]> CC: Kevin Wolf <[email protected]> CC: Max Reitz <[email protected]> CC: Jeff Cody <[email protected]> CC: Eric Blake <[email protected]> --- block/mirror.c | 33 +++++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 7208023..4ecfbf1 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -526,8 +526,37 @@ static int mirror_dirty_init(MirrorBlockJob *s) last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); if (base == NULL && !bdrv_has_zero_init(target_bs)) { - bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); - return 0; + if (!bdrv_can_write_zeroes_with_unmap(target_bs)) { + bdrv_set_dirty_bitmap(s->dirty_bitmap, 0, end); + return 0; + } + + for (sector_num = 0; sector_num < end; ) { + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); + + int nb_sectors = QEMU_ALIGN_DOWN(INT_MAX, s->granularity); + nb_sectors = MIN(nb_sectors >> BDRV_SECTOR_BITS, end - sector_num); + + if (now - last_pause_ns > SLICE_TIME) { + last_pause_ns = now; + block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0); + } + + if (block_job_is_cancelled(&s->common)) { + return 0; + } + + if (s->in_flight >= MAX_IN_FLIGHT) { + trace_mirror_yield(s, s->in_flight, s->buf_free_count, -1); + mirror_wait_for_io(s); + continue; + } + + mirror_do_zero_or_discard(s, sector_num, nb_sectors, false); + sector_num += nb_sectors; + } + + mirror_drain(s); } /* First part, loop on the sectors and initialize the dirty bitmap. */ -- 2.5.0
