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[Qemu-block] [PATCH v2 6/7] mirror: efficiently zero out target
From: |
Denis V. Lunev |
Subject: |
[Qemu-block] [PATCH v2 6/7] mirror: efficiently zero out target |
Date: |
Thu, 7 Jul 2016 12:35:21 +0300 |
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 <address@hidden>
Reviewed-by: Vladimir Sementsov-Ogievskiy<address@hidden>
CC: Stefan Hajnoczi <address@hidden>
CC: Fam Zheng <address@hidden>
CC: Kevin Wolf <address@hidden>
CC: Max Reitz <address@hidden>
CC: Jeff Cody <address@hidden>
CC: Eric Blake <address@hidden>
---
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