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svcrdma: support Remote Invalidation 

Support Remote Invalidation. A private message is exchanged with
the client upon RDMA transport connect that indicates whether
Send With Invalidation may be used by the server to send RPC
replies. The invalidate_rkey is arbitrarily chosen from among
rkeys present in the RPC-over-RDMA header's chunk lists.

Send With Invalidate improves performance only when clients can
recognize, while processing an RPC reply, that an rkey has already
been invalidated. That has been submitted as a separate change.

In the future, the RPC-over-RDMA protocol might support Remote
Invalidation properly. The protocol needs to enable signaling
between peers to indicate when Remote Invalidation can be used
for each individual RPC.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Chuck Lever 2016-09-13 10:53:23 -04:00 committed by J. Bruce Fields
parent cc9d83408b
commit 25d55296dd
3 changed files with 65 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sunrpc/svc_rdma.h
View File

@ -137,6 +137,7 @@ struct svcxprt_rdma {
int sc_ord; /* RDMA read limit */
int sc_max_sge;
int sc_max_sge_rd; /* max sge for read target */
bool sc_snd_w_inv; /* OK to use Send With Invalidate */
atomic_t sc_sq_count; /* Number of SQ WR on queue */
unsigned int sc_sq_depth; /* Depth of SQ */

58
net/sunrpc/xprtrdma/svc_rdma_sendto.c
View File

@ -225,6 +225,48 @@ svc_rdma_get_reply_array(struct rpcrdma_msg *rmsgp,
return rp_ary;
}
/* RPC-over-RDMA Version One private extension: Remote Invalidation.
* Responder's choice: requester signals it can handle Send With
* Invalidate, and responder chooses one rkey to invalidate.
*
* Find a candidate rkey to invalidate when sending a reply. Picks the
* first rkey it finds in the chunks lists.
*
* Returns zero if RPC's chunk lists are empty.
*/
static u32 svc_rdma_get_inv_rkey(struct rpcrdma_msg *rdma_argp,
struct rpcrdma_write_array *wr_ary,
struct rpcrdma_write_array *rp_ary)
{
struct rpcrdma_read_chunk *rd_ary;
struct rpcrdma_segment *arg_ch;
u32 inv_rkey;
inv_rkey = 0;
rd_ary = svc_rdma_get_read_chunk(rdma_argp);
if (rd_ary) {
inv_rkey = be32_to_cpu(rd_ary->rc_target.rs_handle);
goto out;
}
if (wr_ary && be32_to_cpu(wr_ary->wc_nchunks)) {
arg_ch = &wr_ary->wc_array[0].wc_target;
inv_rkey = be32_to_cpu(arg_ch->rs_handle);
goto out;
}
if (rp_ary && be32_to_cpu(rp_ary->wc_nchunks)) {
arg_ch = &rp_ary->wc_array[0].wc_target;
inv_rkey = be32_to_cpu(arg_ch->rs_handle);
goto out;
}
out:
dprintk("svcrdma: Send With Invalidate rkey=%08x\n", inv_rkey);
return inv_rkey;
}
/* Assumptions:
* - The specified write_len can be represented in sc_max_sge * PAGE_SIZE
*/
@ -464,7 +506,8 @@ static int send_reply(struct svcxprt_rdma *rdma,
struct page *page,
struct rpcrdma_msg *rdma_resp,
struct svc_rdma_req_map *vec,
int byte_count)
int byte_count,
u32 inv_rkey)
{
struct svc_rdma_op_ctxt *ctxt;
struct ib_send_wr send_wr;
@ -535,7 +578,11 @@ static int send_reply(struct svcxprt_rdma *rdma,
send_wr.wr_cqe = &ctxt->cqe;
send_wr.sg_list = ctxt->sge;
send_wr.num_sge = sge_no;
send_wr.opcode = IB_WR_SEND;
if (inv_rkey) {
send_wr.opcode = IB_WR_SEND_WITH_INV;
send_wr.ex.invalidate_rkey = inv_rkey;
} else
send_wr.opcode = IB_WR_SEND;
send_wr.send_flags = IB_SEND_SIGNALED;
ret = svc_rdma_send(rdma, &send_wr);
@ -567,6 +614,7 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
int inline_bytes;
struct page *res_page;
struct svc_rdma_req_map *vec;
u32 inv_rkey;
dprintk("svcrdma: sending response for rqstp=%p\n", rqstp);
@ -577,6 +625,10 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
wr_ary = svc_rdma_get_write_array(rdma_argp);
rp_ary = svc_rdma_get_reply_array(rdma_argp, wr_ary);
inv_rkey = 0;
if (rdma->sc_snd_w_inv)
inv_rkey = svc_rdma_get_inv_rkey(rdma_argp, wr_ary, rp_ary);
/* Build an req vec for the XDR */
vec = svc_rdma_get_req_map(rdma);
ret = svc_rdma_map_xdr(rdma, &rqstp->rq_res, vec, wr_ary != NULL);
@ -619,7 +671,7 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
goto err1;
ret = send_reply(rdma, rqstp, res_page, rdma_resp, vec,
inline_bytes);
inline_bytes, inv_rkey);
if (ret < 0)
goto err0;

12
net/sunrpc/xprtrdma/svc_rdma_transport.c
View File

@ -657,9 +657,14 @@ svc_rdma_parse_connect_private(struct svcxprt_rdma *newxprt,
if (pmsg &&
pmsg->cp_magic == rpcrdma_cmp_magic &&
pmsg->cp_version == RPCRDMA_CMP_VERSION) {
dprintk("svcrdma: client send_size %u, recv_size %u\n",
newxprt->sc_snd_w_inv = pmsg->cp_flags &
RPCRDMA_CMP_F_SND_W_INV_OK;
dprintk("svcrdma: client send_size %u, recv_size %u "
"remote inv %ssupported\n",
rpcrdma_decode_buffer_size(pmsg->cp_send_size),
rpcrdma_decode_buffer_size(pmsg->cp_recv_size));
rpcrdma_decode_buffer_size(pmsg->cp_recv_size),
newxprt->sc_snd_w_inv ? "" : "un");
}
}
@ -1093,7 +1098,8 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
dev->attrs.max_fast_reg_page_list_len;
newxprt->sc_dev_caps |= SVCRDMA_DEVCAP_FAST_REG;
newxprt->sc_reader = rdma_read_chunk_frmr;
}
} else
newxprt->sc_snd_w_inv = false;
/*
* Determine if a DMA MR is required and if so, what privs are required