diff options
author | Chuck Lever <chuck.lever@oracle.com> | 2020-05-02 17:37:44 +0300 |
---|---|---|
committer | Chuck Lever <chuck.lever@oracle.com> | 2020-05-18 17:21:21 +0300 |
commit | ca4faf543a33373bed3650812d5f0cd0bd295b1a (patch) | |
tree | 557c33f5f34050f49e27961857ba4e52ad4945da /net/sunrpc/xprtrdma/svc_rdma_sendto.c | |
parent | b9bbe6ed63b2b9f2c9ee5cbd0f2c946a2723f4ce (diff) | |
download | linux-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/xprtrdma/svc_rdma_sendto.c')
-rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_sendto.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c index b6c8643867f2..38e7c3c8c4a9 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c @@ -868,12 +868,10 @@ int svc_rdma_sendto(struct svc_rqst *rqstp) __be32 *p; int ret; - /* Create the RDMA response header. xprt->xpt_mutex, - * acquired in svc_send(), serializes RPC replies. The - * code path below that inserts the credit grant value - * into each transport header runs only inside this - * critical section. - */ + ret = -ENOTCONN; + if (svc_xprt_is_dead(xprt)) + goto err0; + ret = -ENOMEM; sctxt = svc_rdma_send_ctxt_get(rdma); if (!sctxt) |