From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Adrian Bunk <bunk@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Natalie Protasevich <protasnb@gmail.com>,
Kernel Testers List <kernel-testers@vger.kernel.org>,
"Paul E. McKenney" <paulmck@us.ibm.com>
Subject: Re: 2.6.26-rc9-git4: Reported regressions from 2.6.25
Date: Fri, 11 Jul 2008 14:11:59 +1000 [thread overview]
Message-ID: <200807111412.00084.nickpiggin@yahoo.com.au> (raw)
In-Reply-To: <20080710180620.GA30844@elte.hu>
On Friday 11 July 2008 04:06, Ingo Molnar wrote:
> i'm wondering why rcutorture didnt trigger it. I do run !HOTPLUG +
> RCU_PREEMPT kernels and never saw this. Nor did Paul. That aspect is
> weird.
It basically requires an active rcu reader to be preempted (preferably
by something doing a lot of call_rcu or other activity ie. the writer
so it can tick along the different states quickly).
I found just 2 threads (reader and writer) bound to the same CPU would
trigger it fastest, my reader has quite a long rcu read section.
I'm not sure why rcutorture doesn't trigger for everyone. I'm surprised
it does not have much longer maximum read delays -- several ms I would
have thought should be useful to have a crticial section open while the
rcu engine can run through a number of states...
next prev parent reply other threads:[~2008-07-11 4:12 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-08 21:37 Rafael J. Wysocki
2008-07-09 4:49 ` Randy Dunlap
2008-07-09 14:35 ` Rafael J. Wysocki
[not found] ` <200807101725.36175.nickpiggin@yahoo.com.au>
2008-07-10 9:03 ` Kamalesh Babulal
2008-07-10 11:02 ` Alexey Dobriyan
2008-07-10 17:21 ` Linus Torvalds
2008-07-10 17:34 ` Ingo Molnar
2008-07-10 18:06 ` Ingo Molnar
2008-07-11 4:11 ` Nick Piggin [this message]
2008-08-01 21:09 ` Paul E. McKenney
2008-08-01 21:09 ` Paul E. McKenney
[not found] ` <20080710204157.GG6877@linux.vnet.ibm.com>
2008-08-01 21:09 ` Paul E. McKenney
2008-08-01 21:09 ` Paul E. McKenney
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