From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Subject: Re: DISCONTIGMEM is deprecated Date: Sun, 5 May 2019 11:53:23 +0300 Message-ID: <20190505085322.GH15755@rapoport-lnx> References: <20190419094335.GJ18914@techsingularity.net> <20190419140521.GI7751@bombadil.infradead.org> <20190419142835.GM18914@techsingularity.net> <9e7b80a9-b90e-ac04-8b30-b2f285cd4432@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <9e7b80a9-b90e-ac04-8b30-b2f285cd4432@gmx.de> Sender: linux-kernel-owner@vger.kernel.org To: Helge Deller Cc: Mel Gorman , Matthew Wilcox , Andrew Morton , Mikulas Patocka , James Bottomley , linux-parisc@vger.kernel.org, linux-mm@kvack.org, Vlastimil Babka , LKML , linux-arch@vger.kernel.org List-Id: linux-arch.vger.kernel.org Hi, On Fri, Apr 19, 2019 at 10:08:31PM +0200, Helge Deller wrote: > On 19.04.19 16:28, Mel Gorman wrote: > > On Fri, Apr 19, 2019 at 07:05:21AM -0700, Matthew Wilcox wrote: > >> On Fri, Apr 19, 2019 at 10:43:35AM +0100, Mel Gorman wrote: > >>> DISCONTIG is essentially deprecated and even parisc plans to move to > >>> SPARSEMEM so there is no need to be fancy, this patch simply disables > >>> watermark boosting by default on DISCONTIGMEM. > >> > >> I don't think parisc is the only arch which uses DISCONTIGMEM for !NUMA > >> scenarios. Grepping the arch/ directories shows: > >> > >> alpha (does support NUMA, but also non-NUMA DISCONTIGMEM) > >> arc (for supporting more than 1GB of memory) > >> ia64 (looks complicated ...) > >> m68k (for multiple chunks of memory) > >> mips (does support NUMA but also non-NUMA) > >> parisc (both NUMA and non-NUMA) > >> > >> I'm not sure that these architecture maintainers even know that DISCONTIGMEM > >> is deprecated. Adding linux-arch to the cc. > > > > Poor wording then -- yes, DISCONTIGMEM is still used but look where it's > > used. I find it impossible to believe that any new arch would support > > DISCONTIGMEM or that DISCONTIGMEM would be selected when SPARSEMEM is > > available.`It's even more insane when you consider that SPARSEMEM can be > > extended to support VMEMMAP so that it has similar overhead to FLATMEM > > when mapping pfns to struct pages and vice-versa. > > FYI, on parisc we will switch from DISCONTIGMEM to SPARSEMEM with kernel 5.2. > The patch was quite simple and it's currently in the for-next tree: > https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git/commit/?h=for-next&id=281b718721a5e78288271d632731cea9697749f7 A while ago I've sent a patch that removes ARCH_DISCARD_MEMBLOCK option [1] so the hunk below is not needed: diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index c8038165b81f..26c215570adf 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -36,6 +36,7 @@ config PARISC select GENERIC_STRNCPY_FROM_USER select SYSCTL_ARCH_UNALIGN_ALLOW select SYSCTL_EXCEPTION_TRACE + select ARCH_DISCARD_MEMBLOCK select HAVE_MOD_ARCH_SPECIFIC select VIRT_TO_BUS select MODULES_USE_ELF_RELA [1] https://lore.kernel.org/lkml/1556102150-32517-1-git-send-email-rppt@linux.ibm.com/ > Helge > -- Sincerely yours, Mike. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41260 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725873AbfEEIxd (ORCPT ); Sun, 5 May 2019 04:53:33 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x458qBC3033838 for ; Sun, 5 May 2019 04:53:31 -0400 Received: from e06smtp03.uk.ibm.com (e06smtp03.uk.ibm.com [195.75.94.99]) by mx0a-001b2d01.pphosted.com with ESMTP id 2s9r5hfgh1-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Sun, 05 May 2019 04:53:31 -0400 Received: from localhost by e06smtp03.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sun, 5 May 2019 09:53:29 +0100 Date: Sun, 5 May 2019 11:53:23 +0300 From: Mike Rapoport Subject: Re: DISCONTIGMEM is deprecated References: <20190419094335.GJ18914@techsingularity.net> <20190419140521.GI7751@bombadil.infradead.org> <20190419142835.GM18914@techsingularity.net> <9e7b80a9-b90e-ac04-8b30-b2f285cd4432@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9e7b80a9-b90e-ac04-8b30-b2f285cd4432@gmx.de> Message-ID: <20190505085322.GH15755@rapoport-lnx> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Helge Deller Cc: Mel Gorman , Matthew Wilcox , Andrew Morton , Mikulas Patocka , James Bottomley , linux-parisc@vger.kernel.org, linux-mm@kvack.org, Vlastimil Babka , LKML , linux-arch@vger.kernel.org Message-ID: <20190505085323.fpW5gqD9qFZYtJtUDit2yyBT3aBe9DtCbQOfLaZOehc@z> Hi, On Fri, Apr 19, 2019 at 10:08:31PM +0200, Helge Deller wrote: > On 19.04.19 16:28, Mel Gorman wrote: > > On Fri, Apr 19, 2019 at 07:05:21AM -0700, Matthew Wilcox wrote: > >> On Fri, Apr 19, 2019 at 10:43:35AM +0100, Mel Gorman wrote: > >>> DISCONTIG is essentially deprecated and even parisc plans to move to > >>> SPARSEMEM so there is no need to be fancy, this patch simply disables > >>> watermark boosting by default on DISCONTIGMEM. > >> > >> I don't think parisc is the only arch which uses DISCONTIGMEM for !NUMA > >> scenarios. Grepping the arch/ directories shows: > >> > >> alpha (does support NUMA, but also non-NUMA DISCONTIGMEM) > >> arc (for supporting more than 1GB of memory) > >> ia64 (looks complicated ...) > >> m68k (for multiple chunks of memory) > >> mips (does support NUMA but also non-NUMA) > >> parisc (both NUMA and non-NUMA) > >> > >> I'm not sure that these architecture maintainers even know that DISCONTIGMEM > >> is deprecated. Adding linux-arch to the cc. > > > > Poor wording then -- yes, DISCONTIGMEM is still used but look where it's > > used. I find it impossible to believe that any new arch would support > > DISCONTIGMEM or that DISCONTIGMEM would be selected when SPARSEMEM is > > available.`It's even more insane when you consider that SPARSEMEM can be > > extended to support VMEMMAP so that it has similar overhead to FLATMEM > > when mapping pfns to struct pages and vice-versa. > > FYI, on parisc we will switch from DISCONTIGMEM to SPARSEMEM with kernel 5.2. > The patch was quite simple and it's currently in the for-next tree: > https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git/commit/?h=for-next&id=281b718721a5e78288271d632731cea9697749f7 A while ago I've sent a patch that removes ARCH_DISCARD_MEMBLOCK option [1] so the hunk below is not needed: diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index c8038165b81f..26c215570adf 100644 --- a/arch/parisc/Kconfig +++ b/arch/parisc/Kconfig @@ -36,6 +36,7 @@ config PARISC select GENERIC_STRNCPY_FROM_USER select SYSCTL_ARCH_UNALIGN_ALLOW select SYSCTL_EXCEPTION_TRACE + select ARCH_DISCARD_MEMBLOCK select HAVE_MOD_ARCH_SPECIFIC select VIRT_TO_BUS select MODULES_USE_ELF_RELA [1] https://lore.kernel.org/lkml/1556102150-32517-1-git-send-email-rppt@linux.ibm.com/ > Helge > -- Sincerely yours, Mike.