UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

xprtrdma: Streamline rpcrdma_post_recvs 

rb_lock is contended between rpcrdma_buffer_create,
rpcrdma_buffer_put, and rpcrdma_post_recvs.

Commit e340c2d6ef ("xprtrdma: Reduce the doorbell rate (Receive)")
causes rpcrdma_post_recvs to take the rb_lock repeatedly when it
determines more Receives are needed. Streamline this code path so
it takes the lock just once in most cases to build the Receive
chain that is about to be posted.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Chuck Lever 2019-06-19 10:33:26 -04:00 committed by Anna Schumaker
parent 379d1bc5be
commit 9ef33ef5b6
1 changed files with 39 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
net/sunrpc/xprtrdma/verbs.c
View File

@ -1478,11 +1478,13 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
{
struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
struct rpcrdma_ep *ep = &r_xprt->rx_ep;
struct ib_recv_wr *wr, *bad_wr;
struct ib_recv_wr *i, *wr, *bad_wr;
struct rpcrdma_rep *rep;
int needed, count, rc;
rc = 0;
count = 0;
needed = buf->rb_credits + (buf->rb_bc_srv_max_requests << 1);
if (ep->rep_receive_count > needed)
goto out;
@ -1490,39 +1492,48 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
if (!temp)
needed += RPCRDMA_MAX_RECV_BATCH;
count = 0;
/* fast path: all needed reps can be found on the free list */
wr = NULL;
spin_lock(&buf->rb_lock);
while (needed) {
struct rpcrdma_rep *rep;
spin_lock(&buf->rb_lock);
rep = list_first_entry_or_null(&buf->rb_recv_bufs,
struct rpcrdma_rep, rr_list);
if (likely(rep))
list_del(&rep->rr_list);
spin_unlock(&buf->rb_lock);
if (!rep) {
rep = rpcrdma_rep_create(r_xprt, temp);
if (!rep)
break;
}
if (!rpcrdma_regbuf_dma_map(r_xprt, rep->rr_rdmabuf)) {
rpcrdma_recv_buffer_put(rep);
if (!rep)
break;
}
trace_xprtrdma_post_recv(rep->rr_recv_wr.wr_cqe);
list_del(&rep->rr_list);
rep->rr_recv_wr.next = wr;
wr = &rep->rr_recv_wr;
++count;
--needed;
}
if (!count)
spin_unlock(&buf->rb_lock);
while (needed) {
rep = rpcrdma_rep_create(r_xprt, temp);
if (!rep)
break;
rep->rr_recv_wr.next = wr;
wr = &rep->rr_recv_wr;
--needed;
}
if (!wr)
goto out;
for (i = wr; i; i = i->next) {
rep = container_of(i, struct rpcrdma_rep, rr_recv_wr);
if (!rpcrdma_regbuf_dma_map(r_xprt, rep->rr_rdmabuf))
goto release_wrs;
trace_xprtrdma_post_recv(rep->rr_recv_wr.wr_cqe);
++count;
}
rc = ib_post_recv(r_xprt->rx_ia.ri_id->qp, wr,
(const struct ib_recv_wr **)&bad_wr);
out:
trace_xprtrdma_post_recvs(r_xprt, count, rc);
if (rc) {
for (wr = bad_wr; wr;) {
struct rpcrdma_rep *rep;
@ -1534,6 +1545,12 @@ rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
}
}
ep->rep_receive_count += count;
out:
trace_xprtrdma_post_recvs(r_xprt, count, rc);
return;
release_wrs:
for (i = wr; i;) {
rep = container_of(i, struct rpcrdma_rep, rr_recv_wr);
i = i->next;
rpcrdma_recv_buffer_put(rep);
}
}