From: Peter Zijlstra <peterz@infradead.org>
To: Sasha Levin <sasha.levin@oracle.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
fweisbec@gmail.com, tglx@linutronix.de, hpa@zytor.com,
torvalds@linux-foundation.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [tip:sched/core] sched/preempt: Optimize preemption operations on __schedule() callers
Date: Tue, 21 Jul 2015 13:07:00 +0200 [thread overview]
Message-ID: <20150721110700.GN19282@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <55AD72C3.4000300@oracle.com>
On Mon, Jul 20, 2015 at 06:14:27PM -0400, Sasha Levin wrote:
> On 05/19/2015 03:17 AM, tip-bot for Frederic Weisbecker wrote:
> > Commit-ID: b30f0e3ffedfa52b1d67a302ae5860c49998e5e2
> > sched/preempt: Optimize preemption operations on __schedule() callers
> >
> I was seeing RCU stall warnings that appeared to have different backtrace
> each time, but would reliably trigger when fuzzing and looked something like this:
> [4394886.426627] preempt_schedule_irq (./arch/x86/include/asm/paravirt.h:807 kernel/sched/core.c:3218)
The only 'obvious' difference there seems to be something like the
below. Prior to the patch preempt_schedule_irq() used
__preempt_count_{add,sub}() which are the !tracing versions.
Does this make it go again? If not, can you provide a .config?
---
include/linux/preempt.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 84991f185173..235a9f2d76fe 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -139,14 +139,14 @@ extern void preempt_count_sub(int val);
#define preempt_active_enter() \
do { \
- preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
+ __preempt_count_add(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
barrier(); \
} while (0)
#define preempt_active_exit() \
do { \
barrier(); \
- preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
+ __preempt_count_sub(PREEMPT_ACTIVE + PREEMPT_DISABLE_OFFSET); \
} while (0)
#ifdef CONFIG_PREEMPT_COUNT
next prev parent reply other threads:[~2015-07-21 11:07 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-12 14:41 [PATCH 0/6] preempt: A few headers cleanups and preempt_schedule*() optimizations v2 Frederic Weisbecker
2015-05-12 14:41 ` [PATCH 1/6] preempt: Merge preempt_mask.h into preempt.h Frederic Weisbecker
2015-05-19 7:16 ` [tip:sched/core] sched/preempt: " tip-bot for Frederic Weisbecker
2015-05-12 14:41 ` [PATCH 2/6] preempt: Rearrange a few symbols after headers merge Frederic Weisbecker
2015-05-19 7:16 ` [tip:sched/core] sched/preempt: " tip-bot for Frederic Weisbecker
2015-05-12 14:41 ` [PATCH 3/6] preempt: Rename PREEMPT_CHECK_OFFSET to PREEMPT_DISABLE_OFFSET Frederic Weisbecker
2015-05-19 7:16 ` [tip:sched/core] sched/preempt: " tip-bot for Frederic Weisbecker
2015-05-12 14:41 ` [PATCH 4/6] sched: Optimize preemption operations on __schedule() callers Frederic Weisbecker
2015-05-19 7:17 ` [tip:sched/core] sched/preempt: " tip-bot for Frederic Weisbecker
2015-07-20 22:14 ` Sasha Levin
2015-07-20 22:48 ` Frederic Weisbecker
2015-07-20 22:52 ` Sasha Levin
2015-07-21 11:07 ` Peter Zijlstra [this message]
2015-05-12 14:41 ` [PATCH 5/6] preempt: Fix out of date comment Frederic Weisbecker
2015-05-19 7:17 ` [tip:sched/core] sched/preempt: " tip-bot for Frederic Weisbecker
2015-05-12 14:41 ` [PATCH 6/6] preempt: Remove PREEMPT_ACTIVE unmasking off in_atomic() Frederic Weisbecker
2015-05-19 7:17 ` [tip:sched/core] sched/preempt: " tip-bot for Frederic Weisbecker
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