From: Gregory Haskins <gregory.haskins@gmail.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Gregory Haskins <ghaskins@novell.com>,
mingo@elte.hu, rostedt@goodmis.org, tglx@linutronix.de,
linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org
Subject: Re: [PATCH] seqlock: serialize against writers
Date: Fri, 29 Aug 2008 12:10:08 -0400 [thread overview]
Message-ID: <48B81F60.3080409@gmail.com> (raw)
In-Reply-To: <87abevpzv7.fsf@basil.nowhere.org>
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Andi Kleen wrote:
> Gregory Haskins <ghaskins@novell.com> writes:
>
>
>> *Patch submitted for inclusion in PREEMPT_RT 26-rt4. Applies to 2.6.26.3-rt3*
>>
>> Hi Ingo, Steven, Thomas,
>> Please consider for -rt4. This fixes a nasty deadlock on my systems under
>> heavy load.
>>
>
> Does this even work under x86-64? x86-64 uses seqlocks in user space
> in its vsyscalls. And read_lock() definitely doesn't work there because
> it writes.
>
> You would need at least to disable vsyscall gettimeofday(), making
> it much much slower.
>
> Perhaps you tested on one of the systems where the vsyscalls need
> to fallback for other reasons? (e.g. one using pmtimer for timing).
>
> -Andi
>
Im running it on a x86_64 box as we speak. How can I tell if there is a
certain mode that is permitting this?
-Greg
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next prev parent reply other threads:[~2008-08-29 16:12 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-08-29 15:44 [PATCH] seqlock: serialize against writers Gregory Haskins
2008-08-29 16:09 ` Andi Kleen
2008-08-29 16:10 ` Gregory Haskins [this message]
2008-08-29 16:22 ` Andi Kleen
2008-08-29 16:26 ` Gregory Haskins
2008-08-29 16:34 ` Steven Rostedt
2008-08-29 16:35 ` Gregory Haskins
2008-08-29 16:45 ` Andi Kleen
2008-08-29 16:53 ` Steven Rostedt
2008-08-29 17:00 ` Gregory Haskins
2008-08-29 17:00 ` Gregory Haskins
2008-08-29 16:58 ` Steven Rostedt
2008-08-29 16:29 ` Gregory Haskins
2008-08-29 16:37 ` Andi Kleen
2008-08-29 16:41 ` Gregory Haskins
2008-08-29 17:08 ` Andi Kleen
2008-08-29 16:57 ` Stephen Hemminger
2008-08-29 17:02 ` [ RT PATCH] " Steven Rostedt
2008-08-29 18:03 ` [RT PATCH v2] " Gregory Haskins
2008-08-29 18:03 ` Gregory Haskins
2008-08-29 18:12 ` Gregory Haskins
2008-08-30 11:17 ` Peter Zijlstra
2008-08-30 12:32 ` Gregory Haskins
2008-08-30 12:38 ` Peter Zijlstra
2008-08-30 13:05 ` Gregory Haskins
2008-08-30 11:08 ` [PATCH] " Peter Zijlstra
2008-09-02 12:45 ` [RT PATCH v3] " Gregory Haskins
2008-09-02 13:01 ` Gregory Haskins
2008-09-02 13:29 ` [RT PATCH v4] " Gregory Haskins
2008-09-02 13:29 ` Gregory Haskins
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