From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755420AbdERIul (ORCPT ); Thu, 18 May 2017 04:50:41 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:45121 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754679AbdERIud (ORCPT ); Thu, 18 May 2017 04:50:33 -0400 Subject: Re: [PATCH v3 2/2] powerpc/mm/hugetlb: Add support for 1G huge pages To: Michael Ellerman , akpm@linux-foundation.org, Anshuman Khandual Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <1494995292-4443-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1494995292-4443-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <87fug2loze.fsf@concordia.ellerman.id.au> <852b601c-a044-0445-e97d-d17d76ec1154@linux.vnet.ibm.com> <877f1elfga.fsf@concordia.ellerman.id.au> From: "Aneesh Kumar K.V" Date: Thu, 18 May 2017 14:20:24 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <877f1elfga.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17051808-0052-0000-0000-0000020270CF X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007080; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00862140; UDB=6.00427681; IPR=6.00641799; BA=6.00005356; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015499; XFM=3.00000015; UTC=2017-05-18 08:50:31 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17051808-0053-0000-0000-0000509E4B0C Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-18_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705180057 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 18 May 2017 02:17 PM, Michael Ellerman wrote: > "Aneesh Kumar K.V" writes: > >> On Thursday 18 May 2017 10:51 AM, Michael Ellerman wrote: >>> "Aneesh Kumar K.V" writes: >>> >>>> POWER9 supports hugepages of size 2M and 1G in radix MMU mode. This patch >>>> enables the usage of 1G page size for hugetlbfs. This also update the helper >>>> such we can do 1G page allocation at runtime. >>>> >>>> We still don't enable 1G page size on DD1 version. This is to avoid doing >>>> workaround mentioned in commit: 6d3a0379ebdc8 (powerpc/mm: Add >>>> radix__tlb_flush_pte_p9_dd1() >>>> >>>> Signed-off-by: Aneesh Kumar K.V >>>> --- >>>> arch/powerpc/include/asm/book3s/64/hugetlb.h | 10 ++++++++++ >>>> arch/powerpc/mm/hugetlbpage.c | 7 +++++-- >>>> arch/powerpc/platforms/Kconfig.cputype | 1 + >>>> 3 files changed, 16 insertions(+), 2 deletions(-) >>> >>> I think this patch is OK, but it's very confusing because it doesn't >>> mention that it's only talking about *generic* gigantic page support. >> >> What you mean by generic gigantic page ? what is supported here is the >> gigantic page with size 1G alone ? > > What about 16G pages on pseries. > > And all the other gigantic page sizes that Book3E supports? > None of that is supported w.r.t runtime allocation of hugepages. ie, we cannot echo nr_hugepages w.r.t them. For 16GB i am not sure it make sense, because we will rarely get such large contiguous region. W.r.t page size supported for Book3E, may be we can. But I don't have a facility to test those. Hence didn't include that. -aneesh