[Drbd-dev] [PATCH 34/38] drbd: fix "endless" transfer log walk in protocol A
philipp.reisner at linbit.com
Wed Nov 25 11:54:07 CET 2015
From: Lars Ellenberg <lars.ellenberg at linbit.com>
Don't remember a DRBD request as ack_pending, if it is not.
In protocol A, we usually clear RQ_NET_PENDING at the same time we set
RQ_NET_SENT, so when deciding to remember it as ack_pending,
mod_rq_state needs to look at the current request state,
not at the previous state before the current modification was applied.
This should prevent advance_conn_req_ack_pending() from walking the full
transfer log just to find NULL in protocol A, which would cause serious
performance degradation with many "in-flight" requests, e.g. when
working via DRBD-proxy, or with a huge bandwidth-delay product.
Signed-off-by: Philipp Reisner <philipp.reisner at linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg at linbit.com>
drivers/block/drbd/drbd_req.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 7907fb5..2255dcf 100644
@@ -458,7 +458,7 @@ static void mod_rq_state(struct drbd_request *req, struct bio_and_error *m,
atomic_add(req->i.size >> 9, &device->ap_in_flight);
- if (s & RQ_NET_PENDING)
+ if (req->rq_state & RQ_NET_PENDING)
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