From 009a82f6437490c262584d65a14094a818bcb747 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Sat, 9 Mar 2019 12:07:17 -0500 Subject: [PATCH] SUNRPC: Micro-optimise when the task is known not to be sleeping In cases where we know the task is not sleeping, try to optimise away the indirect call to task->tk_action() by replacing it with a direct call. Only change tail calls, to allow gcc to perform tail call elimination. Signed-off-by: Trond Myklebust --- include/linux/sunrpc/sched.h | 8 +++ net/sunrpc/clnt.c | 99 +++++++++++++++++++++++------------- 2 files changed, 73 insertions(+), 34 deletions(-) diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h index 52d41d0c1ae1..ec861cd0cfe8 100644 --- a/include/linux/sunrpc/sched.h +++ b/include/linux/sunrpc/sched.h @@ -304,4 +304,12 @@ rpc_clnt_swap_deactivate(struct rpc_clnt *clnt) } #endif /* CONFIG_SUNRPC_SWAP */ +static inline bool +rpc_task_need_resched(const struct rpc_task *task) +{ + if (RPC_IS_QUEUED(task) || task->tk_callback) + return true; + return false; +} + #endif /* _LINUX_SUNRPC_SCHED_H_ */ diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 67c955d8b21b..498dd6ad5bc5 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -1540,6 +1540,7 @@ call_start(struct rpc_task *task) clnt->cl_stats->rpccnt++; task->tk_action = call_reserve; rpc_task_set_transport(task, clnt); + call_reserve(task); } /* @@ -1553,6 +1554,9 @@ call_reserve(struct rpc_task *task) task->tk_status = 0; task->tk_action = call_reserveresult; xprt_reserve(task); + if (rpc_task_need_resched(task)) + return; + call_reserveresult(task); } static void call_retry_reserve(struct rpc_task *task); @@ -1575,6 +1579,7 @@ call_reserveresult(struct rpc_task *task) if (status >= 0) { if (task->tk_rqstp) { task->tk_action = call_refresh; + call_refresh(task); return; } @@ -1600,6 +1605,7 @@ call_reserveresult(struct rpc_task *task) /* fall through */ case -EAGAIN: /* woken up; retry */ task->tk_action = call_retry_reserve; + call_retry_reserve(task); return; case -EIO: /* probably a shutdown */ break; @@ -1622,6 +1628,9 @@ call_retry_reserve(struct rpc_task *task) task->tk_status = 0; task->tk_action = call_reserveresult; xprt_retry_reserve(task); + if (rpc_task_need_resched(task)) + return; + call_reserveresult(task); } /* @@ -1636,6 +1645,9 @@ call_refresh(struct rpc_task *task) task->tk_status = 0; task->tk_client->cl_stats->rpcauthrefresh++; rpcauth_refreshcred(task); + if (rpc_task_need_resched(task)) + return; + call_refreshresult(task); } /* @@ -1654,6 +1666,7 @@ call_refreshresult(struct rpc_task *task) case 0: if (rpcauth_uptodatecred(task)) { task->tk_action = call_allocate; + call_allocate(task); return; } /* Use rate-limiting and a max number of retries if refresh @@ -1672,6 +1685,7 @@ call_refreshresult(struct rpc_task *task) task->tk_cred_retry--; dprintk("RPC: %5u %s: retry refresh creds\n", task->tk_pid, __func__); + call_refresh(task); return; } dprintk("RPC: %5u %s: refresh creds failed with error %d\n", @@ -1697,8 +1711,10 @@ call_allocate(struct rpc_task *task) task->tk_status = 0; task->tk_action = call_encode; - if (req->rq_buffer) + if (req->rq_buffer) { + call_encode(task); return; + } if (proc->p_proc != 0) { BUG_ON(proc->p_arglen == 0); @@ -1719,8 +1735,12 @@ call_allocate(struct rpc_task *task) status = xprt->ops->buf_alloc(task); xprt_inject_disconnect(xprt); - if (status == 0) + if (status == 0) { + if (rpc_task_need_resched(task)) + return; + call_encode(task); return; + } if (status != -ENOMEM) { rpc_exit(task, status); return; @@ -1803,12 +1823,8 @@ call_encode(struct rpc_task *task) xprt_request_enqueue_receive(task); xprt_request_enqueue_transmit(task); out: - task->tk_action = call_transmit; - /* Check that the connection is OK */ - if (!xprt_bound(task->tk_xprt)) - task->tk_action = call_bind; - else if (!xprt_connected(task->tk_xprt)) - task->tk_action = call_connect; + task->tk_action = call_bind; + call_bind(task); } /* @@ -1842,14 +1858,17 @@ call_bind(struct rpc_task *task) return; } + if (xprt_bound(xprt)) { + task->tk_action = call_connect; + call_connect(task); + return; + } + dprint_status(task); - task->tk_action = call_connect; - if (!xprt_bound(xprt)) { - task->tk_action = call_bind_status; - task->tk_timeout = xprt->bind_timeout; - xprt->ops->rpcbind(task); - } + task->tk_action = call_bind_status; + task->tk_timeout = xprt->bind_timeout; + xprt->ops->rpcbind(task); } /* @@ -1869,6 +1888,7 @@ call_bind_status(struct rpc_task *task) dprint_status(task); task->tk_status = 0; task->tk_action = call_connect; + call_connect(task); return; } @@ -1949,21 +1969,24 @@ call_connect(struct rpc_task *task) return; } + if (xprt_connected(xprt)) { + task->tk_action = call_transmit; + call_transmit(task); + return; + } + dprintk("RPC: %5u call_connect xprt %p %s connected\n", task->tk_pid, xprt, (xprt_connected(xprt) ? "is" : "is not")); - task->tk_action = call_transmit; - if (!xprt_connected(xprt)) { - task->tk_action = call_connect_status; - if (task->tk_status < 0) - return; - if (task->tk_flags & RPC_TASK_NOCONNECT) { - rpc_exit(task, -ENOTCONN); - return; - } - xprt_connect(task); + task->tk_action = call_connect_status; + if (task->tk_status < 0) + return; + if (task->tk_flags & RPC_TASK_NOCONNECT) { + rpc_exit(task, -ENOTCONN); + return; } + xprt_connect(task); } /* @@ -2016,6 +2039,7 @@ call_connect_status(struct rpc_task *task) case 0: clnt->cl_stats->netreconn++; task->tk_action = call_transmit; + call_transmit(task); return; } rpc_exit(task, status); @@ -2040,19 +2064,20 @@ call_transmit(struct rpc_task *task) dprint_status(task); task->tk_action = call_transmit_status; + if (!xprt_prepare_transmit(task)) + return; + task->tk_status = 0; if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) { - if (!xprt_prepare_transmit(task)) + if (!xprt_connected(task->tk_xprt)) { + task->tk_status = -ENOTCONN; return; - task->tk_status = 0; - if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) { - if (!xprt_connected(task->tk_xprt)) { - task->tk_status = -ENOTCONN; - return; - } - xprt_transmit(task); } + xprt_transmit(task); } xprt_end_transmit(task); + if (rpc_task_need_resched(task)) + return; + call_transmit_status(task); } /* @@ -2067,8 +2092,12 @@ call_transmit_status(struct rpc_task *task) * Common case: success. Force the compiler to put this * test first. */ - if (task->tk_status == 0) { - xprt_request_wait_receive(task); + if (rpc_task_transmitted(task)) { + if (task->tk_status == 0) + xprt_request_wait_receive(task); + if (rpc_task_need_resched(task)) + return; + call_status(task); return; } @@ -2129,6 +2158,7 @@ call_bc_encode(struct rpc_task *task) { xprt_request_enqueue_transmit(task); task->tk_action = call_bc_transmit; + call_bc_transmit(task); } /* @@ -2219,6 +2249,7 @@ call_status(struct rpc_task *task) status = task->tk_status; if (status >= 0) { task->tk_action = call_decode; + call_decode(task); return; } -- 2.30.2