[PATCH v4 18/21] xprtrdma: Schedule reply tasklet once per upcall

Chuck Lever
2014-07-22T14:53:35Z

Minor optimization: grab rpcrdma_tk_lock_g and disable hard IRQs
just once after clearing the receive completion queue.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
Tested-by: Shirley Ma <shirley.ma-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Tested-by: Devesh Sharma <devesh.sharma-laKkSmNT4hbQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/verbs.c | 31 +++++++++++++++----------------
1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index f7691be..3563467 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -105,17 +105,6 @@ rpcrdma_run_tasklet(unsigned long data)

static DECLARE_TASKLET(rpcrdma_tasklet_g, rpcrdma_run_tasklet, 0UL);

-static inline void
-rpcrdma_schedule_tasklet(struct rpcrdma_rep *rep)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
- list_add_tail(&rep->rr_list, &rpcrdma_tasklets_g);
- spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);
- tasklet_schedule(&rpcrdma_tasklet_g);
-}
-
static void
rpcrdma_qp_async_error_upcall(struct ib_event *event, void *context)
{
@@ -214,7 +203,7 @@ rpcrdma_sendcq_upcall(struct ib_cq *cq, void *cq_context)
}

static void
-rpcrdma_recvcq_process_wc(struct ib_wc *wc)
+rpcrdma_recvcq_process_wc(struct ib_wc *wc, struct list_head *sched_list)
{
struct rpcrdma_rep *rep =
(struct rpcrdma_rep *)(unsigned long)wc->wr_id;
@@ -245,28 +234,38 @@ rpcrdma_recvcq_process_wc(struct ib_wc *wc)
}

out_schedule:
- rpcrdma_schedule_tasklet(rep);
+ list_add_tail(&rep->rr_list, sched_list);
}

static int
rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
+ struct list_head sched_list;
struct ib_wc *wcs;
int budget, count, rc;
+ unsigned long flags;

+ INIT_LIST_HEAD(&sched_list);
budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
do {
wcs = ep->rep_recv_wcs;

rc = ib_poll_cq(cq, RPCRDMA_POLLSIZE, wcs);
if (rc <= 0)
- return rc;
+ goto out_schedule;

count = rc;
while (count-- > 0)
- rpcrdma_recvcq_process_wc(wcs++);
+ rpcrdma_recvcq_process_wc(wcs++, &sched_list);
} while (rc == RPCRDMA_POLLSIZE && --budget);
- return 0;
+ rc = 0;
+
+out_schedule:
+ spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
+ list_splice_tail(&sched_list, &rpcrdma_tasklets_g);
+ spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);
+ tasklet_schedule(&rpcrdma_tasklet_g);
+ return rc;
}

/*