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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-06-29 23:46:25 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2016-08-22 19:30:25 +0300 |
| commit | 8b355e3bc1408be238ae4695fb6318ae502cae8e (patch) | |
| tree | f923d1cb005f3102e76cd0b2f64567ed80f67c7a /kernel/rcu/tree_trace.c | |
| parent | f7b8eb847e35b18d3ec333774691a905bf16017f (diff) | |
| download | linux-8b355e3bc1408be238ae4695fb6318ae502cae8e.tar.xz | |
rcu: Drive expedited grace periods from workqueue
The current implementation of expedited grace periods has the user
task drive the grace period. This works, but has downsides: (1) The
user task must awaken tasks piggybacking on this grace period, which
can result in latencies rivaling that of the grace period itself, and
(2) User tasks can receive signals, which interfere with RCU CPU stall
warnings.
This commit therefore uses workqueues to drive the grace periods, so
that the user task need not do the awakening. A subsequent commit
will remove the now-unnecessary code allowing for signals.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree_trace.c')
| -rw-r--r-- | kernel/rcu/tree_trace.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c index 86782f9a4604..b1f28972872c 100644 --- a/kernel/rcu/tree_trace.c +++ b/kernel/rcu/tree_trace.c @@ -185,16 +185,17 @@ static int show_rcuexp(struct seq_file *m, void *v) int cpu; struct rcu_state *rsp = (struct rcu_state *)m->private; struct rcu_data *rdp; - unsigned long s1 = 0, s2 = 0, s3 = 0; + unsigned long s0 = 0, s1 = 0, s2 = 0, s3 = 0; for_each_possible_cpu(cpu) { rdp = per_cpu_ptr(rsp->rda, cpu); + s0 += atomic_long_read(&rdp->exp_workdone0); s1 += atomic_long_read(&rdp->exp_workdone1); s2 += atomic_long_read(&rdp->exp_workdone2); s3 += atomic_long_read(&rdp->exp_workdone3); } - seq_printf(m, "s=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n", - rsp->expedited_sequence, s1, s2, s3, + seq_printf(m, "s=%lu wd0=%lu wd1=%lu wd2=%lu wd3=%lu n=%lu enq=%d sc=%lu\n", + rsp->expedited_sequence, s0, s1, s2, s3, atomic_long_read(&rsp->expedited_normal), atomic_read(&rsp->expedited_need_qs), rsp->expedited_sequence / 2); |