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authorChuck Lever <chuck.lever@oracle.com>2020-05-02 17:37:44 +0300
committerChuck Lever <chuck.lever@oracle.com>2020-05-18 17:21:21 +0300
commitca4faf543a33373bed3650812d5f0cd0bd295b1a (patch)
tree557c33f5f34050f49e27961857ba4e52ad4945da /net/sunrpc/svc_xprt.c
parentb9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce (diff)
downloadlinux-ca4faf543a33373bed3650812d5f0cd0bd295b1a.tar.xz
SUNRPC: Move xpt_mutex into socket xpo_sendto methods
It appears that the RPC/RDMA transport does not need serialization of calls to its xpo_sendto method. Move the mutex into the socket methods that still need that serialization. Tail latencies are unambiguously better with this patch applied. fio randrw 8KB 70/30 on NFSv3, smaller numbers are better: clat percentiles (usec): With xpt_mutex: r | 99.99th=[ 8848] w | 99.99th=[ 9634] Without xpt_mutex: r | 99.99th=[ 8586] w | 99.99th=[ 8979] Serializing the construction of RPC/RDMA transport headers is not really necessary at this point, because the Linux NFS server implementation never changes its credit grant on a connection. If that should change, then svc_rdma_sendto will need to serialize access to the transport's credit grant fields. Reported-by: kbuild test robot <lkp@intel.com> [ cel: fix uninitialized variable warning ] Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'net/sunrpc/svc_xprt.c')
-rw-r--r--net/sunrpc/svc_xprt.c12
1 files changed, 3 insertions, 9 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 2284ff038dad..07cdbf7d5764 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -914,16 +914,10 @@ int svc_send(struct svc_rqst *rqstp)
xb->page_len +
xb->tail[0].iov_len;
trace_svc_sendto(xb);
-
- /* Grab mutex to serialize outgoing data. */
- mutex_lock(&xprt->xpt_mutex);
trace_svc_stats_latency(rqstp);
- if (test_bit(XPT_DEAD, &xprt->xpt_flags)
- || test_bit(XPT_CLOSE, &xprt->xpt_flags))
- len = -ENOTCONN;
- else
- len = xprt->xpt_ops->xpo_sendto(rqstp);
- mutex_unlock(&xprt->xpt_mutex);
+
+ len = xprt->xpt_ops->xpo_sendto(rqstp);
+
trace_svc_send(rqstp, len);
svc_xprt_release(rqstp);