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svcrdma: Optimize the logic that selects the R_key to invalidate

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o Select the R_key to invalidate while the CPU cache still contains
  the received RPC Call transport header, rather than waiting until
  we're about to send the RPC Reply.

o Choose Send With Invalidate if there is exactly one distinct R_key
  in the received transport header. If there's more than one, the
  client will have to perform local invalidation after it has
  already waited for remote invalidation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Chuck Lever
2018-11-27 11:11:35 -05:00
committed by J. Bruce Fields
parent b493fd31c0
commit 97bce63408
3 changed files with 77 additions and 40 deletions
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63
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
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@@ -485,6 +485,68 @@ static __be32 *xdr_check_reply_chunk(__be32 *p, const __be32 *end)
return p;
}
/* RPC-over-RDMA Version One private extension: Remote Invalidation.
* Responder's choice: requester signals it can handle Send With
* Invalidate, and responder chooses one R_key to invalidate.
*
* If there is exactly one distinct R_key in the received transport
* header, set rc_inv_rkey to that R_key. Otherwise, set it to zero.
*
* Perform this operation while the received transport header is
* still in the CPU cache.
*/
static void svc_rdma_get_inv_rkey(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
__be32 inv_rkey, *p;
u32 i, segcount;
ctxt->rc_inv_rkey = 0;
if (!rdma->sc_snd_w_inv)
return;
inv_rkey = xdr_zero;
p = ctxt->rc_recv_buf;
p += rpcrdma_fixed_maxsz;
/* Read list */
while (*p++ != xdr_zero) {
p++; /* position */
if (inv_rkey == xdr_zero)
inv_rkey = *p;
else if (inv_rkey != *p)
return;
p += 4;
}
/* Write list */
while (*p++ != xdr_zero) {
segcount = be32_to_cpup(p++);
for (i = 0; i < segcount; i++) {
if (inv_rkey == xdr_zero)
inv_rkey = *p;
else if (inv_rkey != *p)
return;
p += 4;
}
}
/* Reply chunk */
if (*p++ != xdr_zero) {
segcount = be32_to_cpup(p++);
for (i = 0; i < segcount; i++) {
if (inv_rkey == xdr_zero)
inv_rkey = *p;
else if (inv_rkey != *p)
return;
p += 4;
}
}
ctxt->rc_inv_rkey = be32_to_cpu(inv_rkey);
}
/* On entry, xdr->head[0].iov_base points to first byte in the
* RPC-over-RDMA header.
*
@@ -746,6 +808,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return ret;
}
svc_rdma_get_inv_rkey(rdma_xprt, ctxt);
p += rpcrdma_fixed_maxsz;
if (*p != xdr_zero)