Return-Path: Received: from mail-io0-f193.google.com ([209.85.223.193]:33147 "EHLO mail-io0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751394AbdBHXDy (ORCPT ); Wed, 8 Feb 2017 18:03:54 -0500 Received: by mail-io0-f193.google.com with SMTP id 101so527713iom.0 for ; Wed, 08 Feb 2017 15:03:53 -0800 (PST) Subject: [PATCH v3 12/12] sunrpc: Allow keepalive ping on a credit-full transport From: Chuck Lever To: anna.schumaker@netapp.com Cc: linux-rdma@vger.kernel.org, linux-nfs@vger.kernel.org Date: Wed, 08 Feb 2017 17:01:16 -0500 Message-ID: <20170208220116.7152.87626.stgit@manet.1015granger.net> In-Reply-To: <20170208214854.7152.83331.stgit@manet.1015granger.net> References: <20170208214854.7152.83331.stgit@manet.1015granger.net> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: Allow RPC-over-RDMA to send NULL pings even when the transport has hit its credit limit. One RPC-over-RDMA credit is reserved for operations like keepalive. For transports that convey NFSv4, it seems like lease renewal would also be a candidate for using a priority transport slot. I'd like to see a mechanism better than RPCRDMA_PRIORITY that can ensure only one priority operation is in use at a time. Signed-off-by: Chuck Lever --- include/linux/sunrpc/sched.h | 2 ++ net/sunrpc/xprt.c | 4 ++++ net/sunrpc/xprtrdma/transport.c | 3 ++- net/sunrpc/xprtrdma/verbs.c | 13 ++++++++----- 4 files changed, 16 insertions(+), 6 deletions(-) diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h index 13822e6..fcea158 100644 --- a/include/linux/sunrpc/sched.h +++ b/include/linux/sunrpc/sched.h @@ -127,6 +127,7 @@ struct rpc_task_setup { #define RPC_TASK_TIMEOUT 0x1000 /* fail with ETIMEDOUT on timeout */ #define RPC_TASK_NOCONNECT 0x2000 /* return ENOTCONN if not connected */ #define RPC_TASK_NO_RETRANS_TIMEOUT 0x4000 /* wait forever for a reply */ +#define RPC_TASK_NO_CONG 0x8000 /* skip congestion control */ #define RPC_TASK_SOFTPING (RPC_TASK_SOFT | RPC_TASK_SOFTCONN) @@ -137,6 +138,7 @@ struct rpc_task_setup { #define RPC_IS_SOFT(t) ((t)->tk_flags & (RPC_TASK_SOFT|RPC_TASK_TIMEOUT)) #define RPC_IS_SOFTCONN(t) ((t)->tk_flags & RPC_TASK_SOFTCONN) #define RPC_WAS_SENT(t) ((t)->tk_flags & RPC_TASK_SENT) +#define RPC_SKIP_CONG(t) ((t)->tk_flags & RPC_TASK_NO_CONG) #define RPC_TASK_RUNNING 0 #define RPC_TASK_QUEUED 1 diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index b530a28..a477ee6 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -392,6 +392,10 @@ static inline void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *ta { struct rpc_rqst *req = task->tk_rqstp; + if (RPC_SKIP_CONG(task)) { + req->rq_cong = 0; + return 1; + } if (req->rq_cong) return 1; dprintk("RPC: %5u xprt_cwnd_limited cong = %lu cwnd = %lu\n", diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index 3a5a805..073fecd 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -546,7 +546,8 @@ static void rpcrdma_keepalive_release(void *calldata) data = xprt_get(xprt); null_task = rpc_call_null_helper(task->tk_client, xprt, NULL, - RPC_TASK_SOFTPING | RPC_TASK_ASYNC, + RPC_TASK_SOFTPING | RPC_TASK_ASYNC | + RPC_TASK_NO_CONG, &rpcrdma_keepalive_call_ops, data); if (!IS_ERR(null_task)) rpc_put_task(null_task); diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c index 81cd31a..d9b5fa7 100644 --- a/net/sunrpc/xprtrdma/verbs.c +++ b/net/sunrpc/xprtrdma/verbs.c @@ -136,19 +136,20 @@ static void rpcrdma_update_granted_credits(struct rpcrdma_rep *rep) { - struct rpcrdma_msg *rmsgp = rdmab_to_msg(rep->rr_rdmabuf); struct rpcrdma_buffer *buffer = &rep->rr_rxprt->rx_buf; + __be32 *p = rep->rr_rdmabuf->rg_base; u32 credits; if (rep->rr_len < RPCRDMA_HDRLEN_ERR) return; - credits = be32_to_cpu(rmsgp->rm_credit); + credits = be32_to_cpup(p + 2); + if (credits > buffer->rb_max_requests) + credits = buffer->rb_max_requests; + /* Reserve one credit for keepalive ping */ + credits--; if (credits == 0) credits = 1; /* don't deadlock */ - else if (credits > buffer->rb_max_requests) - credits = buffer->rb_max_requests; - atomic_set(&buffer->rb_credits, credits); } @@ -915,6 +916,8 @@ struct rpcrdma_rep * struct rpcrdma_buffer *buf = &r_xprt->rx_buf; int i, rc; + if (r_xprt->rx_data.max_requests < 2) + return -EINVAL; buf->rb_max_requests = r_xprt->rx_data.max_requests; buf->rb_bc_srv_max_requests = 0; atomic_set(&buf->rb_credits, 1);