Re: [Qemu-devel] [PATCH] block/mirror: Sleep periodically during bitmap scanning

[Alexandre DERUMIER <aderumier@odiso.com>]

Hi,

I'm currently testing this patch,
and it still hanging for me (mirroring a raw file from nfs)


I just wonder why block_job_sleep_ns is set to 0 ?

+                block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 0);


I have tried to increasing it to a bigger value

+                block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, 100000000);


And now it's working fine for me, no more qemu hang



----- Mail original -----
De: "Jeff Cody" <jcody@redhat.com>
À: "Fam Zheng" <famz@redhat.com>
Cc: "Kevin Wolf" <kwolf@redhat.com>, "pbonzini" <pbonzini@redhat.com>, "qemu-devel" <qemu-devel@nongnu.org>, qemu-block@nongnu.org
Envoyé: Mardi 16 Juin 2015 06:06:25
Objet: Re: [Qemu-devel] [PATCH] block/mirror: Sleep periodically during	bitmap scanning

On Wed, May 13, 2015 at 11:11:13AM +0800, 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. 
> 
> Add sleep points like the later mirror iterations. 
> 
> Signed-off-by: Fam Zheng <famz@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; 
> -- 
> 2.4.0 
> 

Thanks, applied to my block tree: 
https://github.com/codyprime/qemu-kvm-jtc/commits/block 

Jeff