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authorChuck Lever <chuck.lever@oracle.com>2014-05-28 10:33:51 -0400
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2014-06-04 08:56:45 -0400
commit8301a2c047cc25dabd645e5590c1db0ead4c5af4 (patch)
treeeb9901cc1585570fe8306d05d6d3b381662ef1ce /net
parent1c00dd0776543608e13c74a527660cb8cd28a74f (diff)
downloadlinux-8301a2c047cc25dabd645e5590c1db0ead4c5af4.tar.bz2
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: Chuck Lever <chuck.lever@oracle.com> Acked-by: Sagi Grimberg <sagig@dev.mellanox.co.il> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net')
-rw-r--r--net/sunrpc/xprtrdma/verbs.c10
-rw-r--r--net/sunrpc/xprtrdma/xprt_rdma.h1
2 files changed, 7 insertions, 4 deletions
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index b8caee91661c..1d083664bfca 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -165,8 +165,9 @@ static int
rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
struct ib_wc *wcs;
- int count, rc;
+ int budget, count, rc;
+ budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
do {
wcs = ep->rep_send_wcs;
@@ -177,7 +178,7 @@ rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
count = rc;
while (count-- > 0)
rpcrdma_sendcq_process_wc(wcs++);
- } while (rc == RPCRDMA_POLLSIZE);
+ } while (rc == RPCRDMA_POLLSIZE && --budget);
return 0;
}
@@ -254,8 +255,9 @@ static int
rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
struct ib_wc *wcs;
- int count, rc;
+ int budget, count, rc;
+ budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
do {
wcs = ep->rep_recv_wcs;
@@ -266,7 +268,7 @@ rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
count = rc;
while (count-- > 0)
rpcrdma_recvcq_process_wc(wcs++);
- } while (rc == RPCRDMA_POLLSIZE);
+ } while (rc == RPCRDMA_POLLSIZE && --budget);
return 0;
}
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index cb4c882b97fe..0c3b88ea5edb 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -74,6 +74,7 @@ struct rpcrdma_ia {
* RDMA Endpoint -- one per transport instance
*/
+#define RPCRDMA_WC_BUDGET (128)
#define RPCRDMA_POLLSIZE (16)
struct rpcrdma_ep {