From: Ingo Molnar <mingo@elte.hu>
To: Jamie Lokier <jamie@shareable.org>
Cc: Ulrich Drepper <drepper@redhat.com>,
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 18:03:38 +0200 [thread overview]
Message-ID: <20080815160338.GI27955@elte.hu> (raw)
In-Reply-To: <20080815155457.GA5210@shareable.org>
* Jamie Lokier <jamie@shareable.org> wrote:
> > how about this then?
>
> > +#define MAP_64BIT_STACK 0x20000 /* give out 32bit addresses on old CPUs */
>
> I think the flag makes sense but it's name is confusing - 64BIT for a
> flag which means "maybe request 32-bit stack"! Suggest:
>
> +#define MAP_STACK 0x20000 /* 31bit or 64bit address for stack, */
> + /* whichever is faster on this CPU */
ok. I've applied the patch below to tip/x86/urgent.
> Also, is this _only_ useful for thread stacks, or are there other
> memory allocations where 31-bitness affects execution speed on old
> P4s?
just about anything i guess - but since those CPUs do not really matter
anymore in terms of bleeding-edge performance, what we care about is the
intended current use of this flag: thread stacks.
Ingo
-------------------->
next prev parent reply other threads:[~2008-08-15 16:03 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
2008-08-13 16:02 ` Ingo Molnar
2008-08-15 15:54 ` Jamie Lokier
2008-08-15 16:03 ` Ingo Molnar [this message]
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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