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X-IronPort-AV: E=McAfee;i="6600,9927,10706"; a="378617174" X-IronPort-AV: E=Sophos;i="5.99,266,1677571200"; d="scan'208";a="378617174" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 May 2023 06:07:08 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10706"; a="699706177" X-IronPort-AV: E=Sophos;i="5.99,266,1677571200"; d="scan'208";a="699706177" Received: from avandeve-mobl1.amr.corp.intel.com (HELO [10.209.79.85]) ([10.209.79.85]) by orsmga002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 May 2023 06:07:08 -0700 Message-ID: <9ebd85b6-61da-c868-240d-0ea99c8e147d@linux.intel.com> Date: Thu, 11 May 2023 06:07:07 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [RFC 0/6] mm: improve page allocator scalability via splitting zones Content-Language: en-US To: Jonathan Cameron , Huang Ying Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Mel Gorman , Vlastimil Babka , David Hildenbrand , Johannes Weiner , Dave Hansen , Michal Hocko , Pavel Tatashin , Matthew Wilcox References: <20230511065607.37407-1-ying.huang@intel.com> <20230511113009.00004821@Huawei.com> From: Arjan van de Ven In-Reply-To: <20230511113009.00004821@Huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 30B801C06B7 X-Stat-Signature: z6453peari4mkzir18iy1371eh5n5krj X-HE-Tag: 1683810432-184273 X-HE-Meta: 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 ko5//o0I Rog5vBze6IrFkndISiRB5TM3NfTepA6k/bjlHprom8oIyeWKLonvrVdUrylIBhKbT3kMb/18PRngMQq2M53CV/hOm2+diBn4VatYS9I9vlLdQYHK5ETl37fjF+9vRh71Vwbbv X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 5/11/2023 3:30 AM, Jonathan Cameron wrote: > Hi, > > Interesting idea. I'm curious though on whether this can suffer from > imbalance problems where due to uneven allocations from particular CPUs > you can end up with all page faults happening in one zone and the original > contention problem coming back? Or am I missing some process that will > result in that imbalance being corrected? > > Jonathan Well, the first line of defense is the per cpu page lists... it can well be that a couple of cpus all in the same zone hit some high frequency pattern... that by itself isn't the real issue. Note the "a couple". It gets to be a problem if "a high number" start hitting this... And by splitting the total into smaller pieces, this is going to be much much less likely, since the total number per zone is just less.