Commit 8301a2c0 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker

xprtrdma: Limit work done by completion handler

Sagi Grimberg <sagig@dev.mellanox.co.il> points out that a steady
stream of CQ events could starve other work because of the boundless
loop pooling in rpcrdma_{send,recv}_poll().

Instead of a (potentially infinite) while loop, return after
collecting a budgeted number of completions.
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Acked-by: default avatarSagi Grimberg <sagig@dev.mellanox.co.il>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 1c00dd07
...@@ -165,8 +165,9 @@ static int ...@@ -165,8 +165,9 @@ static int
rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep) rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{ {
struct ib_wc *wcs; struct ib_wc *wcs;
int count, rc; int budget, count, rc;
budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
do { do {
wcs = ep->rep_send_wcs; wcs = ep->rep_send_wcs;
...@@ -177,7 +178,7 @@ rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep) ...@@ -177,7 +178,7 @@ rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
count = rc; count = rc;
while (count-- > 0) while (count-- > 0)
rpcrdma_sendcq_process_wc(wcs++); rpcrdma_sendcq_process_wc(wcs++);
} while (rc == RPCRDMA_POLLSIZE); } while (rc == RPCRDMA_POLLSIZE && --budget);
return 0; return 0;
} }
...@@ -254,8 +255,9 @@ static int ...@@ -254,8 +255,9 @@ static int
rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep) rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{ {
struct ib_wc *wcs; struct ib_wc *wcs;
int count, rc; int budget, count, rc;
budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
do { do {
wcs = ep->rep_recv_wcs; wcs = ep->rep_recv_wcs;
...@@ -266,7 +268,7 @@ rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep) ...@@ -266,7 +268,7 @@ rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
count = rc; count = rc;
while (count-- > 0) while (count-- > 0)
rpcrdma_recvcq_process_wc(wcs++); rpcrdma_recvcq_process_wc(wcs++);
} while (rc == RPCRDMA_POLLSIZE); } while (rc == RPCRDMA_POLLSIZE && --budget);
return 0; return 0;
} }
......
...@@ -74,6 +74,7 @@ struct rpcrdma_ia { ...@@ -74,6 +74,7 @@ struct rpcrdma_ia {
* RDMA Endpoint -- one per transport instance * RDMA Endpoint -- one per transport instance
*/ */
#define RPCRDMA_WC_BUDGET (128)
#define RPCRDMA_POLLSIZE (16) #define RPCRDMA_POLLSIZE (16)
struct rpcrdma_ep { struct rpcrdma_ep {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment