SUNRPC: RPC transport queue must be low latency
rpciod can easily get congested due to the long list of queued rpc_tasks.
Having the receive queue wait in turn for those tasks to complete can
therefore be a bottleneck.
Address the problem by separating the workqueues into:
- rpciod: manages rpc_tasks
- xprtiod: manages transport related work.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index fcfd48d..a9f7862 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -54,7 +54,8 @@
/*
* rpciod-related stuff
*/
-struct workqueue_struct *rpciod_workqueue;
+struct workqueue_struct *rpciod_workqueue __read_mostly;
+struct workqueue_struct *xprtiod_workqueue __read_mostly;
/*
* Disable the timer for a given RPC task. Should be called with
@@ -1071,10 +1072,22 @@
* Create the rpciod thread and wait for it to start.
*/
dprintk("RPC: creating workqueue rpciod\n");
- /* Note: highpri because network receive is latency sensitive */
- wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+ wq = alloc_workqueue("rpciod", WQ_MEM_RECLAIM, 0);
+ if (!wq)
+ goto out_failed;
rpciod_workqueue = wq;
- return rpciod_workqueue != NULL;
+ /* Note: highpri because network receive is latency sensitive */
+ wq = alloc_workqueue("xprtiod", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
+ if (!wq)
+ goto free_rpciod;
+ xprtiod_workqueue = wq;
+ return 1;
+free_rpciod:
+ wq = rpciod_workqueue;
+ rpciod_workqueue = NULL;
+ destroy_workqueue(wq);
+out_failed:
+ return 0;
}
static void rpciod_stop(void)
@@ -1088,6 +1101,9 @@
wq = rpciod_workqueue;
rpciod_workqueue = NULL;
destroy_workqueue(wq);
+ wq = xprtiod_workqueue;
+ xprtiod_workqueue = NULL;
+ destroy_workqueue(wq);
}
void
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 216a138..71df082 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -220,7 +220,7 @@
clear_bit(XPRT_LOCKED, &xprt->state);
smp_mb__after_atomic();
} else
- queue_work(rpciod_workqueue, &xprt->task_cleanup);
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
}
/*
@@ -645,7 +645,7 @@
set_bit(XPRT_CLOSE_WAIT, &xprt->state);
/* Try to schedule an autoclose RPC call */
if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
- queue_work(rpciod_workqueue, &xprt->task_cleanup);
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
xprt_wake_pending_tasks(xprt, -EAGAIN);
spin_unlock_bh(&xprt->transport_lock);
}
@@ -672,7 +672,7 @@
set_bit(XPRT_CLOSE_WAIT, &xprt->state);
/* Try to schedule an autoclose RPC call */
if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
- queue_work(rpciod_workqueue, &xprt->task_cleanup);
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
xprt_wake_pending_tasks(xprt, -EAGAIN);
out:
spin_unlock_bh(&xprt->transport_lock);
@@ -689,7 +689,7 @@
if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
goto out_abort;
spin_unlock(&xprt->transport_lock);
- queue_work(rpciod_workqueue, &xprt->task_cleanup);
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
return;
out_abort:
spin_unlock(&xprt->transport_lock);
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index 62b4f5a..646170d 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1095,7 +1095,7 @@
if (xprt->reestablish_timeout)
xprt->reestablish_timeout = 0;
if (!test_and_set_bit(XPRT_SOCK_DATA_READY, &transport->sock_state))
- queue_work(rpciod_workqueue, &transport->recv_worker);
+ queue_work(xprtiod_workqueue, &transport->recv_worker);
}
read_unlock_bh(&sk->sk_callback_lock);
}
@@ -2378,7 +2378,7 @@
/* Start by resetting any existing state */
xs_reset_transport(transport);
- queue_delayed_work(rpciod_workqueue,
+ queue_delayed_work(xprtiod_workqueue,
&transport->connect_worker,
xprt->reestablish_timeout);
xprt->reestablish_timeout <<= 1;
@@ -2388,7 +2388,7 @@
xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;
} else {
dprintk("RPC: xs_connect scheduled xprt %p\n", xprt);
- queue_delayed_work(rpciod_workqueue,
+ queue_delayed_work(xprtiod_workqueue,
&transport->connect_worker, 0);
}
}