From: Eric Dumazet <dada1@cosmosbay.com>
To: Esben Nielsen <nielsen.esben@googlemail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Oleg Nesterov <oleg@tv-sign.ru>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Nick Piggin <npiggin@suse.de>
Subject: Re: [PATCH 0/2] convert mmap_sem to a scalable rw_mutex
Date: Sat, 12 May 2007 17:26:26 +0200 [thread overview]
Message-ID: <4645DCA2.80408@cosmosbay.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0705121520210.2101@frodo.shire>
Esben Nielsen a écrit :
>
>
> On Sat, 12 May 2007, Peter Zijlstra wrote:
>
>> On Sat, 2007-05-12 at 11:27 +0200, Esben Nielsen wrote:
>>>
>>> On Fri, 11 May 2007, Peter Zijlstra wrote:
>>>
>>>>
>>>> I was toying with a scalable rw_mutex and found that it gives ~10%
>>>> reduction in
>>>> system time on ebizzy runs (without the MADV_FREE patch).
>>>>
>>>
>>> You break priority enheritance on user space futexes! :-(
>>> The problems is that the futex waiter have to take the mmap_sem. And as
>>> your rw_mutex isn't PI enabled you get priority inversions :-(
>>
>> Do note that rwsems have no PI either.
>> PI is not a concern for mainline - yet, I do have ideas here though.
>>
>>
> If PI wasn't a concern for mainline, why is PI futexes merged into the
> mainline?
If you really care about futexes and mmap_sem, just use private futexes, since
they dont use mmap_sem at all.
WARNING: multiple messages have this Message-ID (diff)
From: Eric Dumazet <dada1@cosmosbay.com>
To: Esben Nielsen <nielsen.esben@googlemail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Oleg Nesterov <oleg@tv-sign.ru>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
Nick Piggin <npiggin@suse.de>
Subject: Re: [PATCH 0/2] convert mmap_sem to a scalable rw_mutex
Date: Sat, 12 May 2007 17:26:26 +0200 [thread overview]
Message-ID: <4645DCA2.80408@cosmosbay.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0705121520210.2101@frodo.shire>
Esben Nielsen a ecrit :
>
>
> On Sat, 12 May 2007, Peter Zijlstra wrote:
>
>> On Sat, 2007-05-12 at 11:27 +0200, Esben Nielsen wrote:
>>>
>>> On Fri, 11 May 2007, Peter Zijlstra wrote:
>>>
>>>>
>>>> I was toying with a scalable rw_mutex and found that it gives ~10%
>>>> reduction in
>>>> system time on ebizzy runs (without the MADV_FREE patch).
>>>>
>>>
>>> You break priority enheritance on user space futexes! :-(
>>> The problems is that the futex waiter have to take the mmap_sem. And as
>>> your rw_mutex isn't PI enabled you get priority inversions :-(
>>
>> Do note that rwsems have no PI either.
>> PI is not a concern for mainline - yet, I do have ideas here though.
>>
>>
> If PI wasn't a concern for mainline, why is PI futexes merged into the
> mainline?
If you really care about futexes and mmap_sem, just use private futexes, since
they dont use mmap_sem at all.
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next prev parent reply other threads:[~2007-05-12 15:27 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-11 13:15 [PATCH 0/2] convert mmap_sem to a scalable rw_mutex Peter Zijlstra
2007-05-11 13:15 ` Peter Zijlstra
2007-05-11 13:15 ` [PATCH 1/2] " Peter Zijlstra
2007-05-11 13:15 ` Peter Zijlstra
2007-05-11 14:03 ` Christoph Hellwig
2007-05-11 14:03 ` Christoph Hellwig
2007-05-11 16:31 ` Andrew Morton
2007-05-11 16:31 ` Andrew Morton
2007-05-11 17:07 ` Christoph Lameter
2007-05-11 17:07 ` Christoph Lameter
2007-05-11 18:05 ` Andrew Morton
2007-05-11 18:05 ` Andrew Morton
2007-05-12 18:55 ` Andi Kleen
2007-05-12 18:55 ` Andi Kleen
2007-05-12 18:06 ` Andrew Morton
2007-05-12 18:06 ` Andrew Morton
2007-05-12 18:11 ` Andrew Morton
2007-05-12 18:11 ` Andrew Morton
2007-05-16 23:28 ` Andrew Morton
2007-05-16 23:28 ` Andrew Morton
2007-05-16 23:40 ` Christoph Lameter
2007-05-16 23:40 ` Christoph Lameter
2007-05-17 0:24 ` Andrew Morton
2007-05-17 0:24 ` Andrew Morton
2007-05-12 18:12 ` Oleg Nesterov
2007-05-12 18:12 ` Oleg Nesterov
2007-05-12 19:21 ` Andi Kleen
2007-05-12 19:21 ` Andi Kleen
2007-05-12 21:42 ` Oleg Nesterov
2007-05-12 21:42 ` Oleg Nesterov
2007-05-11 17:57 ` Peter Zijlstra
2007-05-11 17:57 ` Peter Zijlstra
2007-05-11 23:00 ` Oleg Nesterov
2007-05-11 23:00 ` Oleg Nesterov
2007-05-12 7:39 ` Peter Zijlstra
2007-05-12 7:39 ` Peter Zijlstra
2007-05-12 13:41 ` Peter Zijlstra
2007-05-12 13:41 ` Peter Zijlstra
2007-05-12 16:04 ` Oleg Nesterov
2007-05-12 16:04 ` Oleg Nesterov
2007-05-12 16:57 ` Peter Zijlstra
2007-05-12 16:57 ` Peter Zijlstra
2007-05-12 18:03 ` Oleg Nesterov
2007-05-12 18:03 ` Oleg Nesterov
2007-05-14 10:59 ` Peter Zijlstra
2007-05-14 10:59 ` Peter Zijlstra
2007-05-14 11:36 ` Nick Piggin
2007-05-14 11:36 ` Nick Piggin
2007-05-15 0:36 ` Paul E. McKenney
2007-05-15 0:36 ` Paul E. McKenney
2007-05-15 7:43 ` Peter Zijlstra
2007-05-15 7:43 ` Peter Zijlstra
2007-05-15 15:29 ` Paul E. McKenney
2007-05-15 15:29 ` Paul E. McKenney
2007-05-15 16:17 ` Peter Zijlstra
2007-05-15 16:17 ` Peter Zijlstra
2007-05-15 18:52 ` Paul E. McKenney
2007-05-15 18:52 ` Paul E. McKenney
2007-05-11 13:15 ` [PATCH 2/2] mm: change mmap_sem over to the " Peter Zijlstra
2007-05-11 13:15 ` Peter Zijlstra
2007-05-11 16:17 ` Andrew Morton
2007-05-11 16:17 ` Andrew Morton
2007-05-11 17:12 ` Peter Zijlstra
2007-05-11 17:12 ` Peter Zijlstra
2007-05-11 18:08 ` Andrew Morton
2007-05-11 18:08 ` Andrew Morton
2007-05-14 11:54 ` Nick Piggin
2007-05-14 11:54 ` Nick Piggin
2007-05-11 15:56 ` [PATCH 0/2] convert mmap_sem to a " Ingo Molnar
2007-05-11 15:56 ` Ingo Molnar
2007-05-11 16:52 ` Eric Dumazet
2007-05-11 16:52 ` Eric Dumazet
2007-05-11 17:18 ` Peter Zijlstra
2007-05-11 17:18 ` Peter Zijlstra
2007-05-14 12:07 ` Nick Piggin
2007-05-14 12:07 ` Nick Piggin
2007-05-14 12:57 ` Peter Zijlstra
2007-05-14 12:57 ` Peter Zijlstra
2007-05-11 17:08 ` Christoph Lameter
2007-05-11 17:08 ` Christoph Lameter
2007-05-14 11:58 ` Nick Piggin
2007-05-14 11:58 ` Nick Piggin
2007-05-14 12:38 ` Peter Zijlstra
2007-05-14 12:38 ` Peter Zijlstra
2007-05-12 9:27 ` Esben Nielsen
2007-05-12 9:27 ` Esben Nielsen
2007-05-12 10:01 ` Peter Zijlstra
2007-05-12 10:01 ` Peter Zijlstra
2007-05-12 13:44 ` Esben Nielsen
2007-05-12 13:44 ` Esben Nielsen
2007-05-12 14:33 ` Ingo Molnar
2007-05-12 14:33 ` Ingo Molnar
2007-05-12 15:34 ` Esben Nielsen
2007-05-12 15:34 ` Esben Nielsen
2007-05-12 15:42 ` Ingo Molnar
2007-05-12 15:42 ` Ingo Molnar
2007-05-12 15:26 ` Eric Dumazet [this message]
2007-05-12 15:26 ` Eric Dumazet
2007-05-14 8:50 ` Esben Nielsen
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