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| author |   Chuck Lever <chuck.lever@oracle.com> | 2017-06-23 17:18:08 -0400 |
|---|---|---|
| committer |   J. Bruce Fields <bfields@redhat.com> | 2017-06-28 14:21:44 -0400 |
| commit | 2d6491a56c76f2d6c22aaa710e2a4d04ad41529b (patch) | |
| tree | 2ca744381b0491d7c908d1004658e7a8bf16971d /net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | |
| parent | svcrdma: Improve Reply chunk sanity checking (diff) | |
| download | linux-dev-2d6491a56c76f2d6c22aaa710e2a4d04ad41529b.tar.xz linux-dev-2d6491a56c76f2d6c22aaa710e2a4d04ad41529b.zip | |
svcrdma: Don't account for Receive queue "starvation"
>From what I can tell, calling ->recvfrom when there is no work to do
is a normal part of operation. This is the only way svc_recv can
tell when there is no more data ready to receive on the transport.
Neither the TCP nor the UDP transport implementations have a
"starve" metric.
The cost of receive starvation accounting is bumping an atomic, which
results in extra (IMO unnecessary) bus traffic between CPU sockets,
while holding a spin lock.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'net/sunrpc/xprtrdma/svc_rdma_recvfrom.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 21 |
1 files changed, 6 insertions, 15 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c index b48089314f85..1452bd02d857 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c @@ -844,9 +844,9 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) struct svc_xprt *xprt = rqstp->rq_xprt; struct svcxprt_rdma *rdma_xprt = container_of(xprt, struct svcxprt_rdma, sc_xprt); - struct svc_rdma_op_ctxt *ctxt = NULL; + struct svc_rdma_op_ctxt *ctxt; struct rpcrdma_msg *rmsgp; - int ret = 0; + int ret; dprintk("svcrdma: rqstp=%p\n", rqstp); @@ -863,21 +863,13 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) struct svc_rdma_op_ctxt, list); list_del(&ctxt->list); } else { - atomic_inc(&rdma_stat_rq_starve); + /* No new incoming requests, terminate the loop */ clear_bit(XPT_DATA, &xprt->xpt_flags); - ctxt = NULL; + spin_unlock(&rdma_xprt->sc_rq_dto_lock); + return 0; } spin_unlock(&rdma_xprt->sc_rq_dto_lock); - if (!ctxt) { - /* This is the EAGAIN path. The svc_recv routine will - * return -EAGAIN, the nfsd thread will go to call into - * svc_recv again and we shouldn't be on the active - * transport list - */ - if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) - goto defer; - goto out; - } + dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p\n", ctxt, rdma_xprt, rqstp); atomic_inc(&rdma_stat_recv); @@ -920,7 +912,6 @@ complete: + rqstp->rq_arg.page_len + rqstp->rq_arg.tail[0].iov_len; svc_rdma_put_context(ctxt, 0); - out: dprintk("svcrdma: ret=%d, rq_arg.len=%u, " "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zd\n", ret, rqstp->rq_arg.len, |