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| author |   Chuck Lever <chuck.lever@oracle.com> | 2019-10-17 14:31:53 -0400 |
|---|---|---|
| committer |   Anna Schumaker <Anna.Schumaker@Netapp.com> | 2019-10-24 10:30:40 -0400 |
| commit | 614f3c96d7e5efd1c4dc699524857130a52c6a7f (patch) | |
| tree | 05b6a845cd5731657b7f63c5af28a597b2bedd38 /net/sunrpc/xprtrdma/backchannel.c | |
| parent | xprtrdma: Refactor rpcrdma_prepare_msg_sges() (diff) | |
| download | linux-dev-614f3c96d7e5efd1c4dc699524857130a52c6a7f.tar.xz linux-dev-614f3c96d7e5efd1c4dc699524857130a52c6a7f.zip | |
xprtrdma: Pull up sometimes
On some platforms, DMA mapping part of a page is more costly than
copying bytes. Restore the pull-up code and use that when we
think it's going to be faster. The heuristic for now is to pull-up
when the size of the RPC message body fits in the buffer underlying
the head iovec.
Indeed, not involving the I/O MMU can help the RPC/RDMA transport
scale better for tiny I/Os across more RDMA devices. This is because
interaction with the I/O MMU is eliminated, as is handling a Send
completion, for each of these small I/Os. Without the explicit
unmapping, the NIC no longer needs to do a costly internal TLB shoot
down for buffers that are just a handful of bytes.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'net/sunrpc/xprtrdma/backchannel.c')
| -rw-r--r-- | net/sunrpc/xprtrdma/backchannel.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c index 50e075fcdd8f..11685245546a 100644 --- a/net/sunrpc/xprtrdma/backchannel.c +++ b/net/sunrpc/xprtrdma/backchannel.c @@ -79,7 +79,7 @@ static int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) *p = xdr_zero; if (rpcrdma_prepare_send_sges(r_xprt, req, RPCRDMA_HDRLEN_MIN, - &rqst->rq_snd_buf, rpcrdma_noch)) + &rqst->rq_snd_buf, rpcrdma_noch_pullup)) return -EIO; trace_xprtrdma_cb_reply(rqst); |