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From: Ulrich Drepper <drepper@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: 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: Wed, 13 Aug 2008 08:55:26 -0700	[thread overview]
Message-ID: <48A303EE.8070002@redhat.com> (raw)
In-Reply-To: <20080813154043.GA11886@elte.hu>

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Ingo Molnar wrote:
> Btw., can you see any problems with option #1: simply removing MAP_32BIT 
> from 64-bit stack allocations in glibc unconditionally?

Yes, as we both agree, there are still such machines out there.

The real problem is: what to do if somebody complains?  If we would have
the extra flag such people could be accommodated.  If there is no such
flag then distributions cannot just add the flag (it's part of the
kernel API) and they would be caught between a rock and a hard place.
Option #2 provides the biggest flexibility.

I upstream kernel truly doesn't care about such machines anymore there
are two options:

- - really do nothing at all

- - at least reserve a flag in case somebody wants/has to implement option
  #2

- --
a?? Ulrich Drepper a?? Red Hat, Inc. a?? 444 Castro St a?? Mountain View, CA a??
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  reply	other threads:[~2008-08-13 15:55 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <af8810200808121736q76640cc1kb814385072fe9b29@mail.gmail.com>
2008-08-13  0:45 ` Pardo
2008-08-13 10:44   ` Ingo Molnar
2008-08-13 13:35     ` Arjan van de Ven
2008-08-13 14:21       ` Ulrich Drepper
2008-08-13 14:25         ` Ingo Molnar
2008-08-13 14:36           ` Ulrich Drepper
2008-08-13 15:10             ` Ingo Molnar
2008-08-13 15:21               ` Ulrich Drepper
2008-08-13 15:40                 ` Ingo Molnar
2008-08-13 15:55                   ` Ulrich Drepper [this message]
2008-08-13 16:02                     ` Ingo Molnar
2008-08-15 15:54                       ` Jamie Lokier
2008-08-15 16:03                         ` Ingo Molnar
2008-08-15 17:13                         ` Ulrich Drepper
2008-08-15 17:19                           ` Ingo Molnar
2008-08-15 17:23                             ` Ulrich Drepper
2008-08-15 19:00                               ` Ingo Molnar
2008-08-13 17:09                     ` Linus Torvalds
2008-08-13 18:04                       ` Ulrich Drepper
2008-08-13 18:16                         ` Arjan van de Ven
2008-08-13 18:22                           ` Ulrich Drepper
2008-08-13 16:05                 ` H. Peter Anvin
2008-08-13 20:42               ` Andi Kleen
2008-08-13 20:56                 ` Andrew Morton
2008-08-13 21:46                   ` Andi Kleen
2008-08-15 12:43                 ` Ingo Molnar
2008-08-15 13:33                   ` Andi Kleen

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