svcrdma: Persistently allocate and DMA-map Send buffers

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While sending each RPC Reply, svc_rdma_sendto allocates and DMA-
maps a separate buffer where the RPC/RDMA transport header is
constructed. The buffer is unmapped and released in the Send
completion handler. This is significant per-RPC overhead,
especially for small RPCs.

Instead, allocate and DMA-map a buffer, and cache it in each
svc_rdma_send_ctxt. This buffer and its mapping can be re-used
for each RPC, saving the cost of memory allocation and DMA
mapping.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

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This commit is contained in:

Chuck Lever 2018-05-07 15:28:25 -04:00 • committed by J. Bruce Fields

parent 3abb03face

commit 99722fe4d5

4 changed files with 105 additions and 128 deletions

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8

include/linux/sunrpc/svc_rdma.h

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51

net/sunrpc/xprtrdma/svc_rdma_backchannel.c

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25

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

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149

net/sunrpc/xprtrdma/svc_rdma_sendto.c

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