From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp06.au.ibm.com (e23smtp06.au.ibm.com [202.81.31.148]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp06.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 683E12C00B6 for ; Fri, 12 Apr 2013 15:53:37 +1000 (EST) Received: from /spool/local by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 12 Apr 2013 15:47:55 +1000 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [9.190.235.21]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 8E5E8357804A for ; Fri, 12 Apr 2013 15:53:32 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r3C5qvZL12517834 for ; Fri, 12 Apr 2013 15:52:57 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r3C5r1Rr016527 for ; Fri, 12 Apr 2013 15:53:02 +1000 Date: Fri, 12 Apr 2013 15:39:47 +1000 From: David Gibson To: "Aneesh Kumar K.V" Subject: Re: [PATCH -V5 17/25] powerpc/THP: Implement transparent hugepages for ppc64 Message-ID: <20130412053947.GI5065@truffula.fritz.box> References: <1365055083-31956-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1365055083-31956-18-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20130411053823.GE8165@truffula.fritz.box> <87sj2xms5u.fsf@linux.vnet.ibm.com> <20130412005135.GA5065@truffula.fritz.box> <8761zsmj65.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="WHz+neNWvhIGAO8A" In-Reply-To: <8761zsmj65.fsf@linux.vnet.ibm.com> Cc: paulus@samba.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --WHz+neNWvhIGAO8A Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Apr 12, 2013 at 10:36:58AM +0530, Aneesh Kumar K.V wrote: > David Gibson writes: >=20 > > On Thu, Apr 11, 2013 at 01:10:29PM +0530, Aneesh Kumar K.V wrote: > >> David Gibson writes: > >>=20 > >> > On Thu, Apr 04, 2013 at 11:27:55AM +0530, Aneesh Kumar K.V wrote: > >> >> From: "Aneesh Kumar K.V" > >> >>=20 > >> >> We now have pmd entries covering to 16MB range. To implement THP on= powerpc, > >> >> we double the size of PMD. The second half is used to deposit the p= gtable (PTE page). > >> >> We also use the depoisted PTE page for tracking the HPTE informatio= n. The information > >> >> include [ secondary group | 3 bit hidx | valid ]. We use one byte p= er each HPTE entry. > >> >> With 16MB hugepage and 64K HPTE we need 256 entries and with 4K HPT= E we need > >> >> 4096 entries. Both will fit in a 4K PTE page. > >> >>=20 > >> >> Signed-off-by: Aneesh Kumar K.V > >> >> --- > >> >> arch/powerpc/include/asm/page.h | 2 +- > >> >> arch/powerpc/include/asm/pgtable-ppc64-64k.h | 3 +- > >> >> arch/powerpc/include/asm/pgtable-ppc64.h | 2 +- > >> >> arch/powerpc/include/asm/pgtable.h | 240 ++++++++++++++= ++++++ > >> >> arch/powerpc/mm/pgtable.c | 314 ++++++++++++++= ++++++++++++ > >> >> arch/powerpc/mm/pgtable_64.c | 13 ++ > >> >> arch/powerpc/platforms/Kconfig.cputype | 1 + > >> >> 7 files changed, 572 insertions(+), 3 deletions(-) > >> >>=20 > >> >> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include= /asm/page.h > >> >> index 38e7ff6..b927447 100644 > >> >> --- a/arch/powerpc/include/asm/page.h > >> >> +++ b/arch/powerpc/include/asm/page.h > >> >> @@ -40,7 +40,7 @@ > >> >> #ifdef CONFIG_HUGETLB_PAGE > >> >> extern unsigned int HPAGE_SHIFT; > >> >> #else > >> >> -#define HPAGE_SHIFT PAGE_SHIFT > >> >> +#define HPAGE_SHIFT PMD_SHIFT > >> > > >> > That looks like it could break everything except the 64k page size > >> > 64-bit base. > >>=20 > >> How about=20 > > > > It seems very dubious to me to have transparent hugepages enabled > > without explicit hugepages in the first place. > > >=20 > IMHO once we have THP, we will not be using explicit hugepages unless we > want 16GB pages. We still can't go breaking the combination in the interim. Especially if users are already in the habit of invoking things with libhugetlbfs. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --WHz+neNWvhIGAO8A Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iEYEARECAAYFAlFnniMACgkQaILKxv3ab8YEkgCfTgzvvlhBT7NPiDeBmIPw3l6G 3XoAn0V1ou3spdJ2MTyfwp+aWwA6v6oI =DdOB -----END PGP SIGNATURE----- --WHz+neNWvhIGAO8A--