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RDMA_MSGP type calls insert a zero pad in the middle of the RPC message to align the RPC request's data payload to the server's alignment preferences. A server can then "page flip" the payload into place to avoid a data copy in certain circumstances. However: 1. The client has to have a priori knowledge of the server's preferred alignment 2. Requests eligible for RDMA_MSGP are requests that are small enough to have been sent inline, and convey a data payload at the _end_ of the RPC message Today 1. is done with a sysctl, and is a global setting that is copied during mount. Linux does not support CCP to query the server's preferences (RFC 5666, Section 6). A small-ish NFSv3 WRITE might use RDMA_MSGP, but no NFSv4 compound fits bullet 2. Thus the Linux client currently leaves RDMA_MSGP disabled. The Linux server handles RDMA_MSGP, but does not use any special page flipping, so it confers no benefit. Clean up the marshaling code by removing the logic that constructs RDMA_MSGP type calls. This also reduces the maximum send iovec size from four to just two elements. /proc/sys/sunrpc/rdma_inline_write_padding is a kernel API, and thus is left in place. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Tested-by: Devesh Sharma <devesh.sharma@avagotech.com> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com> |
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| .. | ||
| fmr_ops.c | ||
| frwr_ops.c | ||
| Makefile | ||
| module.c | ||
| physical_ops.c | ||
| rpc_rdma.c | ||
| svc_rdma_marshal.c | ||
| svc_rdma_recvfrom.c | ||
| svc_rdma_sendto.c | ||
| svc_rdma_transport.c | ||
| svc_rdma.c | ||
| transport.c | ||
| verbs.c | ||
| xprt_rdma.h | ||