Hi Yehuda,
while running tests with qemu-io I've been experiencing a lot of
messages when running a large writev request (several hundred MB in
a single call):
10.06.20 22:10:07.337108 b67dcb70 client4136.objecter pg 3.437e on [0] is laggy: 33
10.06.20 22:10:07.337708 b67dcb70 client4136.objecter pg 3.2553 on [0] is laggy: 19
[...]
Everything is working fine, though. I think that the large number of
queued requests is the cause for this behaviour and I would propose to
delay futher requests (see attached patch).
What do you think about it?
Another question: I there a way to figure out max_osd through librados?
Christian
---
block/rbd.c | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/block/rbd.c b/block/rbd.c
index 74589cb..241b0c6 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -47,6 +47,14 @@
#define OBJ_MAX_SIZE (1UL << OBJ_DEFAULT_OBJ_ORDER)
+/*
+ * For best performance MAX_RADOS_REQS should be at least as large as the
+ * number of osds. It may be larger, but if to high you may experience lagging
+ *
+ * XXX: automatically set to 2*max_osd ???
+ */
+#define MAX_RADOS_REQS 16
+
typedef struct RBDAIOCB {
BlockDriverAIOCB common;
QEMUBH *bh;
@@ -507,6 +515,11 @@ static BlockDriverAIOCB *rbd_aio_rw_vector(BlockDriverState *bs,
rcb->segsize = segsize;
rcb->buf = buf;
+ /* delay rados aio requests when the queue is getting to large */
+ while ((segnr - last_segnr + acb->aiocnt) > MAX_RADOS_REQS) {
+ usleep(100);
+ }
+
if (write) {
rados_aio_create_completion(rcb, NULL,
(rados_callback_t) rbd_finish_aiocb,
--
1.7.0.4
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
