From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f200.google.com (mail-io0-f200.google.com [209.85.223.200]) by kanga.kvack.org (Postfix) with ESMTP id 9F04A28089F for ; Thu, 9 Feb 2017 00:06:58 -0500 (EST) Received: by mail-io0-f200.google.com with SMTP id q20so14086181ioi.0 for ; Wed, 08 Feb 2017 21:06:58 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. 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Violators will be prosecuted for from ; Thu, 9 Feb 2017 15:06:54 +1000 Received: from d23relay06.au.ibm.com (d23relay06.au.ibm.com [9.185.63.219]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 2CB563578057 for ; Thu, 9 Feb 2017 16:06:51 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay06.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v1956hxU31785022 for ; Thu, 9 Feb 2017 16:06:51 +1100 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v1956Ih3008306 for ; Thu, 9 Feb 2017 16:06:19 +1100 Subject: Re: [PATCH 3/3] mm: Enable Buddy allocation isolation for CDM nodes References: <20170208140148.16049-1-khandual@linux.vnet.ibm.com> <20170208140148.16049-4-khandual@linux.vnet.ibm.com> <8ef1de25-d4fd-482c-c55e-df93d0730484@suse.cz> From: Anshuman Khandual Date: Thu, 9 Feb 2017 10:35:58 +0530 MIME-Version: 1.0 In-Reply-To: <8ef1de25-d4fd-482c-c55e-df93d0730484@suse.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Message-Id: <8982ccfc-3b96-89bd-60e6-471971aee609@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka , Anshuman Khandual , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: mhocko@suse.com, mgorman@suse.de, minchan@kernel.org, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, srikar@linux.vnet.ibm.com, haren@linux.vnet.ibm.com, jglisse@redhat.com, dave.hansen@intel.com, dan.j.williams@intel.com On 02/08/2017 10:48 PM, Vlastimil Babka wrote: > On 02/08/2017 03:01 PM, Anshuman Khandual wrote: >> This implements allocation isolation for CDM nodes in buddy allocator by >> discarding CDM memory zones all the time except in the cases where the >> gfp >> flag has got __GFP_THISNODE or the nodemask contains CDM nodes in cases >> where it is non NULL (explicit allocation request in the kernel or user >> process MPOL_BIND policy based requests). >> >> Signed-off-by: Anshuman Khandual >> --- >> mm/page_alloc.c | 19 +++++++++++++++++++ >> 1 file changed, 19 insertions(+) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 40908de..7d8c82a 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -64,6 +64,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -2908,6 +2909,24 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned >> int order, int alloc_flags, >> struct page *page; >> unsigned long mark; >> >> + /* >> + * CDM nodes get skipped if the requested gfp flag >> + * does not have __GFP_THISNODE set or the nodemask >> + * does not have any CDM nodes in case the nodemask >> + * is non NULL (explicit allocation requests from >> + * kernel or user process MPOL_BIND policy which has >> + * CDM nodes). >> + */ >> + if (is_cdm_node(zone->zone_pgdat->node_id)) { >> + if (!(gfp_mask & __GFP_THISNODE)) { >> + if (!ac->nodemask) >> + continue; >> + >> + if (!nodemask_has_cdm(*ac->nodemask)) >> + continue; > > nodemask_has_cdm() looks quite expensive, combined with the loop here > that's O(n^2). But I don't understand why you need it. If there is no > cdm node in the nodemask, then we never reach this code with a cdm node, > because the zonelist iterator already checks the nodemask? Am I missing > something? A CDM zone can be selected during zonelist iteration if (1) If nodemask is NULL (where all zones are eligible) (1) Skip it if __GFP_THISNODE is not mentioned (2) Pick it if __GFP_THISNODE is mentioned (2) If nodemask has CDM (where CDM zones are eligible) (1) Pick it if nodemask has CDM (2) Pick it if __GFP_THISNODE is mentioned (1) (1) Enforces the primary isolation (2) (1) Is the only option which could be O(n^2) as the worst case Checking for both the zone being a CDM zone and the nodemask containing CDM node has to happen together for (2) (1). But we dont run into this option unless we have first checked if request contains __GFP_THISNODE and that nodemask is really a non NULL value. Hence the number cases getting into (2) (1) should be less. IIUC only the user space MPOL_BIND ones will come here. -- 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