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| author |   Chuck Lever <chuck.lever@oracle.com> | 2021-02-09 10:32:20 -0500 |
|---|---|---|
| committer | Chuck Lever <chuck.lever@oracle.com> | 2021-08-17 11:47:53 -0400 |
| commit | b6c2bfea096ba22583f1071c10ce0745804b9b95 (patch) | |
| tree | d6a74441d55852b6335b4fe935300550d2bb993a /net/sunrpc | |
| parent | svcrdma: Fewer calls to wake_up() in Send completion handler (diff) | |
| download | linux-dev-b6c2bfea096ba22583f1071c10ce0745804b9b95.tar.xz linux-dev-b6c2bfea096ba22583f1071c10ce0745804b9b95.zip | |
svcrdma: Relieve contention on sc_send_lock.
/proc/lock_stat indicates the the sc_send_lock is heavily
contended when the server is under load from a single client.
To address this, convert the send_ctxt free list to an llist.
Returning an item to the send_ctxt cache is now waitless, which
reduces the instruction path length in the single-threaded Send
handler (svc_rdma_wc_send).
The goal is to enable the ib_comp_wq worker to handle a higher
RPC/RDMA Send completion rate given the same CPU resources. This
change reduces CPU utilization of Send completion by 2-3% on my
server.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-By: Tom Talpey <tom@talpey.com>
Diffstat (limited to 'net/sunrpc')
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_sendto.c | 23 | ||||
| -rw-r--r-- | net/sunrpc/xprtrdma/svc_rdma_transport.c | 2 |
2 files changed, 9 insertions, 16 deletions
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c index fba2ee4eb607..599021b2391d 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c @@ -113,13 +113,6 @@ static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc); -static inline struct svc_rdma_send_ctxt * -svc_rdma_next_send_ctxt(struct list_head *list) -{ - return list_first_entry_or_null(list, struct svc_rdma_send_ctxt, - sc_list); -} - static void svc_rdma_send_cid_init(struct svcxprt_rdma *rdma, struct rpc_rdma_cid *cid) { @@ -182,9 +175,10 @@ fail0: void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma) { struct svc_rdma_send_ctxt *ctxt; + struct llist_node *node; - while ((ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts))) { - list_del(&ctxt->sc_list); + while ((node = llist_del_first(&rdma->sc_send_ctxts)) != NULL) { + ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node); ib_dma_unmap_single(rdma->sc_pd->device, ctxt->sc_sges[0].addr, rdma->sc_max_req_size, @@ -204,12 +198,13 @@ void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma) struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma) { struct svc_rdma_send_ctxt *ctxt; + struct llist_node *node; spin_lock(&rdma->sc_send_lock); - ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts); - if (!ctxt) + node = llist_del_first(&rdma->sc_send_ctxts); + if (!node) goto out_empty; - list_del(&ctxt->sc_list); + ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node); spin_unlock(&rdma->sc_send_lock); out: @@ -253,9 +248,7 @@ void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma, ctxt->sc_sges[i].length); } - spin_lock(&rdma->sc_send_lock); - list_add(&ctxt->sc_list, &rdma->sc_send_ctxts); - spin_unlock(&rdma->sc_send_lock); + llist_add(&ctxt->sc_node, &rdma->sc_send_ctxts); } /** diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c index d94b7759ada1..99474078c304 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c @@ -136,7 +136,7 @@ static struct svcxprt_rdma *svc_rdma_create_xprt(struct svc_serv *serv, svc_xprt_init(net, &svc_rdma_class, &cma_xprt->sc_xprt, serv); INIT_LIST_HEAD(&cma_xprt->sc_accept_q); INIT_LIST_HEAD(&cma_xprt->sc_rq_dto_q); - INIT_LIST_HEAD(&cma_xprt->sc_send_ctxts); + init_llist_head(&cma_xprt->sc_send_ctxts); init_llist_head(&cma_xprt->sc_recv_ctxts); INIT_LIST_HEAD(&cma_xprt->sc_rw_ctxts); init_waitqueue_head(&cma_xprt->sc_send_wait); |