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From: Chuck Lever <chuck.lever@oracle.com>
To: anna.schumaker@netapp.com
Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org
Subject: [PATCH v1 03/23] xprtrdma: Reduce the doorbell rate (Receive)
Date: Mon, 11 Feb 2019 11:23:54 -0500
Message-ID: <20190211162354.2817.81043.stgit@manet.1015granger.net> (raw)
In-Reply-To: <20190211161920.2817.20881.stgit@manet.1015granger.net>

Post RECV WRs in batches to reduce the hardware doorbell rate per
transport. This helps the RPC-over-RDMA client scale better in
number of transports.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/verbs.c     |    2 ++
 net/sunrpc/xprtrdma/xprt_rdma.h |   10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 4994e75..b4e997d 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1480,6 +1480,8 @@ struct rpcrdma_regbuf *
 	if (ep->rep_receive_count > needed)
 		goto out;
 	needed -= ep->rep_receive_count;
+	if (!temp)
+		needed += RPCRDMA_MAX_RECV_BATCH;
 
 	count = 0;
 	wr = NULL;
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 33db208..10f6593 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -205,6 +205,16 @@ struct rpcrdma_rep {
 	struct ib_recv_wr	rr_recv_wr;
 };
 
+/* To reduce the rate at which a transport invokes ib_post_recv
+ * (and thus the hardware doorbell rate), xprtrdma posts Receive
+ * WRs in batches.
+ *
+ * Setting this to zero disables Receive post batching.
+ */
+enum {
+	RPCRDMA_MAX_RECV_BATCH = 7,
+};
+
 /* struct rpcrdma_sendctx - DMA mapped SGEs to unmap after Send completes
  */
 struct rpcrdma_req;


  parent reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-11 16:23 [PATCH v1 00/23] NFS client patches for v5.1 (complete) Chuck Lever
2019-02-11 16:23 ` [PATCH v1 01/23] xprtrdma: Fix sparse warnings Chuck Lever
2019-02-11 16:23 ` [PATCH v1 02/23] xprtrdma: Check inline size before providing a Write chunk Chuck Lever
2019-02-11 16:23 ` Chuck Lever [this message]
2019-02-11 16:24 ` [PATCH v1 04/23] SUNRPC: Display symbolic flag names in RPC trace events Chuck Lever
2019-02-11 16:24 ` [PATCH v1 05/23] SUNRPC: Add xdr_stream::rqst field Chuck Lever
2019-02-11 16:24 ` [PATCH v1 06/23] SUNRPC: Add XDR overflow trace event Chuck Lever
2019-02-11 16:24 ` [PATCH v1 07/23] SUNRPC: Add trace event that reports reply page vector alignment Chuck Lever
2019-02-11 16:24 ` [PATCH v1 08/23] NFS: Remove print_overflow_msg() Chuck Lever
2019-02-11 16:24 ` [PATCH v1 09/23] NFS: Add trace events to report non-zero NFS status codes Chuck Lever
2019-02-11 16:24 ` [PATCH v1 10/23] SUNRPC: Remove some dprintk() call sites from auth functions Chuck Lever
2019-02-11 16:24 ` [PATCH v1 11/23] SUNRPC: Remove rpc_xprt::tsh_size Chuck Lever
2019-02-11 16:24 ` [PATCH v1 12/23] SUNRPC: Add build option to disable support for insecure enctypes Chuck Lever
2019-02-11 16:24 ` [PATCH v1 13/23] SUNRPC: Use struct xdr_stream when constructing RPC Call header Chuck Lever
2019-02-11 16:24 ` [PATCH v1 14/23] SUNRPC: Clean up rpc_verify_header() Chuck Lever
2019-02-11 16:24 ` [PATCH v1 15/23] SUNRPC: Use struct xdr_stream when decoding RPC Reply header Chuck Lever
2019-02-11 16:25 ` [PATCH v1 16/23] SUNRPC: Introduce trace points in rpc_auth_gss.ko Chuck Lever
2019-02-11 16:25 ` [PATCH v1 17/23] SUNRPC: Remove xdr_buf_trim() Chuck Lever
2019-02-11 16:25 ` [PATCH v1 18/23] SUNRPC: Add SPDX IDs to some net/sunrpc/auth_gss/ files Chuck Lever
2019-02-11 16:25 ` [PATCH v1 19/23] SUNRPC: Introduce rpc_prepare_reply_pages() Chuck Lever
2019-02-11 16:25 ` [PATCH v1 20/23] NFS: Account for XDR pad of buf->pages Chuck Lever
2019-04-05 17:36   ` Olga Kornievskaia
2019-04-05 17:51     ` Chuck Lever
2019-04-05 19:17       ` Olga Kornievskaia
2019-04-05 19:23         ` Chuck Lever
2019-04-05 19:27           ` Olga Kornievskaia
2019-04-05 19:42             ` Chuck Lever
2019-04-08 14:36               ` Olga Kornievskaia
2019-04-08 14:43                 ` Chuck Lever
2019-04-08 15:21                   ` Olga Kornievskaia
2019-04-08 15:26                     ` Olga Kornievskaia
2019-04-08 15:50                       ` Olga Kornievskaia
2019-04-08 16:02                         ` Olga Kornievskaia
2019-04-08 16:29                         ` Chuck Lever
2019-02-11 16:25 ` [PATCH v1 21/23] SUNRPC: Make AUTH_SYS and AUTH_NULL set au_verfsize Chuck Lever
2019-02-11 16:25 ` [PATCH v1 22/23] SUNRPC: Add rpc_auth::au_ralign field Chuck Lever
2019-02-11 16:25 ` [PATCH v1 23/23] SUNRPC: Use au_rslack when computing reply buffer size Chuck Lever

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