linux-kernel - [PATCH] Inline double_unlock

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <200811051857.14944.sripathik@in.ibm.com>
Date:	Wed, 5 Nov 2008 18:57:14 +0530
From:	Sripathi Kodi <sripathik@...ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH] Inline double_unlock_balance()

Hi,

We have a test case which measures the variation in the amount of time 
needed to perform a fixed amount of work on the preempt_rt kernel. We 
started seeing deterioration in it's performance recently. The test 
should never take more than 10 microseconds, but we started 5-10% 
failure rate. Using elimination method, we traced the problem to commit 
1b12bbc747560ea68bcc132c3d05699e52271da0 (lockdep: re-annotate 
scheduler runqueues). When LOCKDEP is disabled, this patch only adds an 
additional function call to double_unlock_balance(). Hence I inlined 
double_unlock_balance() and the problem went away. Here is a patch to 
make this change.

Thanks,
Sripathi.

lockdep: Inline double_unlock_balance()

Additional function call for double_unlock_balance() causes latency 
problems for some test cases on the preempt_rt kernel.

Signed-off-by: Sripathi Kodi <sripathik@...ibm.com>

Index: linux-2.6.27.4/kernel/sched.c
===================================================================
--- linux-2.6.27.4.orig/kernel/sched.c	2008-11-05 05:01:01.000000000 -0800
+++ linux-2.6.27.4/kernel/sched.c	2008-11-05 05:01:20.000000000 -0800
@@ -2812,7 +2812,7 @@
 	return ret;
 }

-static void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
+static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
 	__releases(busiest->lock)
 {
 	spin_unlock(&busiest->lock);
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/