Chuck Lever 6720a89933 xprtrdma: Fix latency regression on NUMA NFS/RDMA clients ... With v4.15, on one of my NFS/RDMA clients I measured a nearly doubling in the latency of small read and write system calls. There was no change in server round trip time. The extra latency appears in the whole RPC execution path. "git bisect" settled on commit ccede75985 ("xprtrdma: Spread reply processing over more CPUs") . After some experimentation, I found that leaving the WQ bound and allowing the scheduler to pick the dispatch CPU seems to eliminate the long latencies, and it does not introduce any new regressions. The fix is implemented by reverting only the part of commit ccede75985 ("xprtrdma: Spread reply processing over more CPUs") that dispatches RPC replies specifically on the CPU where the matching RPC call was made. Interestingly, saving the CPU number and later queuing reply processing there was effective _only_ for a NFS READ and WRITE request. On my NUMA client, in-kernel RPC reply processing for asynchronous RPCs was dispatched on the same CPU where the RPC call was made, as expected. However synchronous RPCs seem to get their reply dispatched on some other CPU than where the call was placed, every time. Fixes: ccede75985 ("xprtrdma: Spread reply processing over ... ") Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>		2018-04-10 16:06:22 -04:00
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backchannel.c	xprtrdma: Correct some documenting comments	2018-01-23 09:44:39 -05:00
fmr_ops.c	xprtrdma: Add trace points to instrument memory invalidation	2018-01-23 09:44:36 -05:00
frwr_ops.c	xprtrdma: Add trace points to instrument memory invalidation	2018-01-23 09:44:36 -05:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
module.c	rpcrdma: infrastructure for static trace points in rpcrdma.ko	2018-01-23 09:44:25 -05:00
rpc_rdma.c	xprtrdma: Fix latency regression on NUMA NFS/RDMA clients	2018-04-10 16:06:22 -04:00
svc_rdma_backchannel.c	svcrdma: Post Receives in the Receive completion handler	2018-01-18 11:52:51 -05:00
svc_rdma_recvfrom.c	svcrdma: Post Receives in the Receive completion handler	2018-01-18 11:52:51 -05:00
svc_rdma_rw.c	svcrdma: Fix Read chunk round-up	2018-02-08 13:40:17 -05:00
svc_rdma_sendto.c	svcrdma: Post Receives in the Receive completion handler	2018-01-18 11:52:51 -05:00
svc_rdma_transport.c	svcrdma: Post Receives in the Receive completion handler	2018-01-18 11:52:51 -05:00
svc_rdma.c	svcrdma: Reduce size of sge array in struct svc_rdma_op_ctxt	2017-04-25 17:25:55 -04:00
transport.c	xprtrdma: Fix latency regression on NUMA NFS/RDMA clients	2018-04-10 16:06:22 -04:00
verbs.c	xprtrdma: Fix BUG after a device removal	2018-02-02 13:31:04 -05:00
xprt_rdma.h	xprtrdma: Fix latency regression on NUMA NFS/RDMA clients	2018-04-10 16:06:22 -04:00