Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755916AbYGaOdN (ORCPT ); Thu, 31 Jul 2008 10:33:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751240AbYGaOc6 (ORCPT ); Thu, 31 Jul 2008 10:32:58 -0400 Received: from ozlabs.org ([203.10.76.45]:45829 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751216AbYGaOc5 (ORCPT ); Thu, 31 Jul 2008 10:32:57 -0400 Subject: Re: [RFC] [PATCH 0/5 V2] Huge page backed user-space stacks From: Michael Ellerman Reply-To: michael@ellerman.id.au To: Mel Gorman Cc: Nick Piggin , linux-mm@kvack.org, libhugetlbfs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Eric Munson , Andrew Morton In-Reply-To: <20080731135016.GG1704@csn.ul.ie> References: <200807311626.15709.nickpiggin@yahoo.com.au> <20080731112734.GE1704@csn.ul.ie> <200807312151.56847.nickpiggin@yahoo.com.au> <20080731135016.GG1704@csn.ul.ie> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-ZnN6y2vs7iwYgoQWASLw" Date: Fri, 01 Aug 2008 00:32:55 +1000 Message-Id: <1217514775.19050.41.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2738 Lines: 84 --=-ZnN6y2vs7iwYgoQWASLw Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, 2008-07-31 at 14:50 +0100, Mel Gorman wrote: > On (31/07/08 21:51), Nick Piggin didst pronounce: > > On Thursday 31 July 2008 21:27, Mel Gorman wrote: > > > On (31/07/08 16:26), Nick Piggin didst pronounce: > >=20 > > > > I imagine it should be, unless you're using a CPU with seperate TLB= s for > > > > small and huge pages, and your large data set is mapped with huge p= ages, > > > > in which case you might now introduce *new* TLB contention between = the > > > > stack and the dataset :) > > > > > > Yes, this can happen particularly on older CPUs. For example, on my > > > crash-test laptop the Pentium III there reports > > > > > > TLB and cache info: > > > 01: Instruction TLB: 4KB pages, 4-way set assoc, 32 entries > > > 02: Instruction TLB: 4MB pages, 4-way set assoc, 2 entries > >=20 > > Oh? Newer CPUs tend to have unified TLBs? > >=20 >=20 > I've seen more unified DTLBs (ITLB tends to be split) than not but it cou= ld > just be where I'm looking. For example, on the machine I'm writing this > (Core Duo), it's >=20 > TLB and cache info: > 51: Instruction TLB: 4KB and 2MB or 4MB pages, 128 entries > 5b: Data TLB: 4KB and 4MB pages, 64 entries >=20 > DTLB is unified there but on my T60p laptop where I guess they want the C= PU > to be using less power and be cheaper, it's >=20 > TLB info > Instruction TLB: 4K pages, 4-way associative, 128 entries. > Instruction TLB: 4MB pages, fully associative, 2 entries > Data TLB: 4K pages, 4-way associative, 128 entries. > Data TLB: 4MB pages, 4-way associative, 8 entries Clearly I've been living under a rock, but I didn't know one could get such nicely formatted info. In case I'm not the only one, a bit of googling turned up "x86info", courtesy of davej - apt-get'able and presumably yum'able too. cheers --=20 Michael Ellerman OzLabs, IBM Australia Development Lab wwweb: http://michael.ellerman.id.au phone: +61 2 6212 1183 (tie line 70 21183) We do not inherit the earth from our ancestors, we borrow it from our children. - S.M.A.R.T Person --=-ZnN6y2vs7iwYgoQWASLw Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBIkc0XdSjSd0sB4dIRAjiFAKC/PVum23IXYylNmt+uZqHg6DDT4wCdGQqp QYIRIcLptVPjBPD/Yma2Tqs= =HNGl -----END PGP SIGNATURE----- --=-ZnN6y2vs7iwYgoQWASLw-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/