From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0708.google.com with SMTP id f25so937044rvb.26 for ; Fri, 15 Aug 2008 10:13:46 -0700 (PDT) Message-ID: <48A5B943.1010607@gmail.com> Date: Fri, 15 Aug 2008 10:13:39 -0700 From: Ulrich Drepper MIME-Version: 1.0 Subject: Re: pthread_create() slow for many threads; also time to revisit 64b context switch optimization? References: <20080813104445.GA24632@elte.hu> <20080813063533.444c650d@infradead.org> <48A2EE07.3040003@redhat.com> <20080813142529.GB21129@elte.hu> <48A2F157.7000303@redhat.com> <20080813151007.GA8780@elte.hu> <48A2FC17.9070302@redhat.com> <20080813154043.GA11886@elte.hu> <48A303EE.8070002@redhat.com> <20080813160218.GB18037@elte.hu> <20080815155457.GA5210@shareable.org> In-Reply-To: <20080815155457.GA5210@shareable.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Jamie Lokier Cc: Ingo Molnar , Arjan van de Ven , 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 , Thomas Gleixner , "H. Peter Anvin" List-ID: -----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 -----END PGP SIGNATURE----- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org