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From: Ulrich Drepper <drepper@gmail.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	Arjan van de Ven <arjan@infradead.org>,
	akpm@linux-foundation.org, hugh@veritas.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, briangrant@google.com,
	cgd@google.com, mbligh@google.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: pthread_create() slow for many threads; also time to revisit 64b context switch optimization?
Date: Fri, 15 Aug 2008 10:13:39 -0700	[thread overview]
Message-ID: <48A5B943.1010607@gmail.com> (raw)
In-Reply-To: <20080815155457.GA5210@shareable.org>

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Jamie Lokier wrote:
> Suggest:
> 
> +#define MAP_STACK       0x20000         /* 31bit or 64bit address for stack, */
> +                                        /* whichever is faster on this CPU */

I agree.  Except for the comment.


> Also, is this _only_ useful for thread stacks, or are there other
> memory allocations where 31-bitness affects execution speed on old P4s?

Actually, I would define the flag as "do whatever is best assuming the
allocation is used for stacks".

For instance, minimally the /proc/*/maps output could show "[user
stack]" or something like this.  For security, perhaps, setting of
PROC_EXEC can be prevented.
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Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org

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WARNING: multiple messages have this Message-ID (diff)
From: Ulrich Drepper <drepper@gmail.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: Ingo Molnar <mingo@elte.hu>,
	Arjan van de Ven <arjan@infradead.org>,
	akpm@linux-foundation.org, hugh@veritas.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, briangrant@google.com,
	cgd@google.com, mbligh@google.com,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: pthread_create() slow for many threads; also time to revisit 64b context switch optimization?
Date: Fri, 15 Aug 2008 10:13:39 -0700	[thread overview]
Message-ID: <48A5B943.1010607@gmail.com> (raw)
In-Reply-To: <20080815155457.GA5210@shareable.org>

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Jamie Lokier wrote:
> Suggest:
> 
> +#define MAP_STACK       0x20000         /* 31bit or 64bit address for stack, */
> +                                        /* whichever is faster on this CPU */

I agree.  Except for the comment.


> Also, is this _only_ useful for thread stacks, or are there other
> memory allocations where 31-bitness affects execution speed on old P4s?

Actually, I would define the flag as "do whatever is best assuming the
allocation is used for stacks".

For instance, minimally the /proc/*/maps output could show "[user
stack]" or something like this.  For security, perhaps, setting of
PROC_EXEC can be prevented.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.9 (GNU/Linux)
Comment: Using GnuPG with Fedora - http://enigmail.mozdev.org

iEYEARECAAYFAkiluUMACgkQ2ijCOnn/RHSb5gCfb5VhiLA/wbamoAVqfxR32k4N
tSIAoK/KAmwcVd+RjkPnb9RSuAeL/KLV
=2ynl
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  parent reply	other threads:[~2008-08-15 17:13 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <af8810200808121736q76640cc1kb814385072fe9b29@mail.gmail.com>
2008-08-13  0:45 ` pthread_create() slow for many threads; also time to revisit 64b context switch optimization? Pardo
2008-08-13  0:45   ` Pardo
2008-08-13 10:44   ` Ingo Molnar
2008-08-13 10:44     ` Ingo Molnar
2008-08-13 13:35     ` Arjan van de Ven
2008-08-13 13:35       ` Arjan van de Ven
2008-08-13 14:21       ` Ulrich Drepper
2008-08-13 14:21         ` Ulrich Drepper
2008-08-13 14:25         ` Ingo Molnar
2008-08-13 14:25           ` Ingo Molnar
2008-08-13 14:36           ` Ulrich Drepper
2008-08-13 14:36             ` Ulrich Drepper
2008-08-13 15:10             ` Ingo Molnar
2008-08-13 15:10               ` Ingo Molnar
2008-08-13 15:21               ` Ulrich Drepper
2008-08-13 15:21                 ` Ulrich Drepper
2008-08-13 15:40                 ` Ingo Molnar
2008-08-13 15:40                   ` Ingo Molnar
2008-08-13 15:55                   ` Ulrich Drepper
2008-08-13 15:55                     ` Ulrich Drepper
2008-08-13 16:02                     ` Ingo Molnar
2008-08-13 16:02                       ` Ingo Molnar
2008-08-15 15:54                       ` Jamie Lokier
2008-08-15 15:54                         ` Jamie Lokier
2008-08-15 16:03                         ` Ingo Molnar
2008-08-15 16:03                           ` Ingo Molnar
2008-08-15 17:13                         ` Ulrich Drepper [this message]
2008-08-15 17:13                           ` Ulrich Drepper
2008-08-15 17:19                           ` Ingo Molnar
2008-08-15 17:19                             ` Ingo Molnar
2008-08-15 17:23                             ` Ulrich Drepper
2008-08-15 17:23                               ` Ulrich Drepper
2008-08-15 19:00                               ` Ingo Molnar
2008-08-15 19:00                                 ` Ingo Molnar
2008-08-13 17:09                     ` Linus Torvalds
2008-08-13 17:09                       ` Linus Torvalds
2008-08-13 18:04                       ` Ulrich Drepper
2008-08-13 18:04                         ` Ulrich Drepper
2008-08-13 18:16                         ` Arjan van de Ven
2008-08-13 18:16                           ` Arjan van de Ven
2008-08-13 18:22                           ` Ulrich Drepper
2008-08-13 18:22                             ` Ulrich Drepper
2008-08-13 16:05                 ` H. Peter Anvin
2008-08-13 16:05                   ` H. Peter Anvin
2008-08-13 20:42               ` Andi Kleen
2008-08-13 20:42                 ` Andi Kleen
2008-08-13 20:56                 ` Andrew Morton
2008-08-13 20:56                   ` Andrew Morton
2008-08-13 21:46                   ` Andi Kleen
2008-08-13 21:46                     ` Andi Kleen
2008-08-15 12:43                 ` Ingo Molnar
2008-08-15 12:43                   ` Ingo Molnar
2008-08-15 13:33                   ` Andi Kleen
2008-08-15 13:33                     ` Andi Kleen
2008-08-21 16:35 Leon Bottou

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