From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org,
linux-rt-users <linux-rt-users@vger.kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Carsten Emde <C.Emde@osadl.org>, John Kacur <jkacur@redhat.com>
Subject: [PATCH RT 04/12] Latency histograms: Detect another yet overlooked sharedprio condition
Date: Tue, 17 Jul 2012 11:31:19 -0400 [thread overview]
Message-ID: <20120717153243.340760961@goodmis.org> (raw)
In-Reply-To: 20120717153115.606116459@goodmis.org
[-- Attachment #1: 0004-Latency-histograms-Detect-another-yet-overlooked-sha.patch --]
[-- Type: text/plain, Size: 1159 bytes --]
From: Carsten Emde <C.Emde@osadl.org>
While waiting for an RT process to be woken up, the previous process may
go to wait and switch to another one with the same priority which then
becomes current. This condition was not correctly recognized and led to
erroneously high latency recordings during periods of low CPU load.
This patch correctly marks such latencies as sharedprio and prevents
them from being recorded as actual system latency.
Signed-off-by: Carsten Emde <C.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/latency_hist.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/trace/latency_hist.c b/kernel/trace/latency_hist.c
index d514eef..6a4c869 100644
--- a/kernel/trace/latency_hist.c
+++ b/kernel/trace/latency_hist.c
@@ -935,6 +935,9 @@ static notrace void probe_wakeup_latency_hist_stop(void *v,
goto out;
}
+ if (current->prio == cpu_wakeup_task->prio)
+ per_cpu(wakeup_sharedprio, cpu) = 1;
+
/*
* The task we are waiting for is about to be switched to.
* Calculate latency and store it in histogram.
--
1.7.10.4
next prev parent reply other threads:[~2012-07-17 15:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-17 15:31 [PATCH RT 00/12] [ANNOUNCE] 3.4.4-rt14-rc2 stable review Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 01/12] Latency histogramms: Cope with backwards running local trace clock Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 02/12] Latency histograms: Adjust timer, if already elapsed when programmed Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 03/12] Disable RT_GROUP_SCHED in PREEMPT_RT_FULL Steven Rostedt
2012-07-17 15:31 ` Steven Rostedt [this message]
2012-07-17 15:31 ` [PATCH RT 05/12] slab: Prevent local lock deadlock Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 06/12] fs, jbd: pull your plug when waiting for space Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 07/12] perf: Make swevent hrtimer run in irq instead of softirq Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 08/12] cpu/rt: Rework cpu down for PREEMPT_RT Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 09/12] cpu/rt: Fix cpu_hotplug variable initialization Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 10/12] workqueue: Revert workqueue: Fix PF_THREAD_BOUND abuse Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 11/12] workqueue: Revert workqueue: Fix cpuhotplug trainwreck Steven Rostedt
2012-07-17 15:31 ` [PATCH RT 12/12] Linux 3.4.4-rt14-rc2 Steven Rostedt
-- strict thread matches above, loose matches on Subject: below --
2012-07-18 22:39 [PATCH RT 00/12] [ANNOUNCE] 3.0.36-rt58-rc1 stable review Steven Rostedt
2012-07-18 22:39 ` [PATCH RT 04/12] Latency histograms: Detect another yet overlooked sharedprio condition Steven Rostedt
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