On 07/27/2016 05:26 AM, Alexandre Derumier wrote:
ceph force writethrough until a flush is detected.
With cache=unsafe, we never send flush.
So we need to tell to ceph
to set rbd_cache_writethrough_until_flush=false in this case.
This speedup a lot qemu-img convert which use cache=unsafe by default
Signed-off-by: Alexandre Derumier <aderumier@xxxxxxxxx>
Sorry for the delay - this is correct and needed since this option
appeared by default in Ceph hammer.
Reviewed-by: Josh Durgin <jdurgin@xxxxxxxxxx>
---
block/rbd.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/block/rbd.c b/block/rbd.c
index 0106fea..f3af6c8 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -552,6 +552,10 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
rados_conf_set(s->cluster, "rbd_cache", "true");
}
+ if (flags & BDRV_O_NO_FLUSH) {
+ rados_conf_set(s->cluster, "rbd_cache_writethrough_until_flush", "false");
+ }
+
r = rados_connect(s->cluster);
if (r < 0) {
error_setg_errno(errp, -r, "error connecting");
--
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