On Wed, 05/13 13:17, Wen Congyang wrote: > On 05/13/2015 11:11 AM, Fam Zheng wrote: > > Before, we only yield after initializing dirty bitmap, where the QMP > > command would return. That may take very long, and guest IO will be > > blocked. > > Do you have such case to reproduce it? If the disk image is too larger, > and I think qemu doesn't cache all metedata in the memory. So we will > yield in bdrv_is_allocated_above() when we read the metedata from the > disk.
True for qcow2, but raw-posix has no such yield points, because it uses lseek(..., SEEK_HOLE). I do have a reproducer - just try a big raw image on your ext4. Fam > > Thanks > Wen Congyang > > > > > Add sleep points like the later mirror iterations. > > > > Signed-off-by: Fam Zheng <f...@redhat.com> > > --- > > block/mirror.c | 13 ++++++++++++- > > 1 file changed, 12 insertions(+), 1 deletion(-) > > > > diff --git a/block/mirror.c b/block/mirror.c > > index 1a1d997..baed225 100644 > > --- a/block/mirror.c > > +++ b/block/mirror.c > > @@ -467,11 +467,23 @@ static void coroutine_fn mirror_run(void *opaque) > > sectors_per_chunk = s->granularity >> BDRV_SECTOR_BITS; > > mirror_free_init(s); > > > > + last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); > > if (!s->is_none_mode) { > > /* First part, loop on the sectors and initialize the dirty > > bitmap. */ > > BlockDriverState *base = s->base; > > for (sector_num = 0; sector_num < end; ) { > > int64_t next = (sector_num | (sectors_per_chunk - 1)) + 1; > > + int64_t now = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); > > + > > + 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)) { > > + goto immediate_exit; > > + } > > + > > ret = bdrv_is_allocated_above(bs, base, > > sector_num, next - sector_num, > > &n); > > > > @@ -490,7 +502,6 @@ static void coroutine_fn mirror_run(void *opaque) > > } > > > > bdrv_dirty_iter_init(s->dirty_bitmap, &s->hbi); > > - last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME); > > for (;;) { > > uint64_t delay_ns = 0; > > int64_t cnt; > > >