Date: Wed, 13 Aug 2008 11:16:35 -0700
From: Arjan van de Ven <arjan@infradead.org>
To: Ulrich Drepper <drepper@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, 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,
       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?
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On Wed, 13 Aug 2008 11:04:29 -0700
Ulrich Drepper <drepper@redhat.com> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Linus Torvalds wrote:
> > Ulrich, I don't understand why you worry more about a _potential_
> > (and fairly unlikely) complaint, than about a real one today.
> 
> Of course I care.  All I try to do is to prevent going from one
> extreme (all focus on P4s) to the other (ignore P4s completely).

(fwiw as far as I know this is only about early 64 bit P4s, not later
generations)
> 
> Even ignoring this one case here, I think it's in any case useful for
> userlevel to tell the kernel that an anonymous memory region is needed
> for a stack.  This might allow better optimizations and/or security
> implementations.

yeah maybe we should also tell it we expect it to be used downwards.
Oh wait.. MAP_GROWSDOWN ?

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