From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F11CC433DF for ; Thu, 2 Jul 2020 01:50:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ED3552082F for ; Thu, 2 Jul 2020 01:50:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED3552082F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 515398D0008; Wed, 1 Jul 2020 21:50:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 49F328D0001; Wed, 1 Jul 2020 21:50:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 366B78D0008; Wed, 1 Jul 2020 21:50:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0064.hostedemail.com [216.40.44.64]) by kanga.kvack.org (Postfix) with ESMTP id 1C97C8D0001 for ; Wed, 1 Jul 2020 21:50:57 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8ACCB2C8B for ; Thu, 2 Jul 2020 01:50:56 +0000 (UTC) X-FDA: 76991457312.05.ducks49_4d05aca26e85 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 6B15B1801B5EA for ; Thu, 2 Jul 2020 01:50:56 +0000 (UTC) X-HE-Tag: ducks49_4d05aca26e85 X-Filterd-Recvd-Size: 3096 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Thu, 2 Jul 2020 01:50:55 +0000 (UTC) IronPort-SDR: PfzVbsD3v5yymtN+RMv7j4RhrqejpJISu22SRUfsMTEZ1SO3I1tRm4/5uBMrX5En/6C5iqchlj FHZ5LMVVlaUQ== X-IronPort-AV: E=McAfee;i="6000,8403,9669"; a="211812696" X-IronPort-AV: E=Sophos;i="5.75,302,1589266800"; d="scan'208";a="211812696" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Jul 2020 18:50:54 -0700 IronPort-SDR: 7ngpAIGWRv/c5y+XeTgGVcInhOKwoTmi+67M1QB8Tw3pjutP15zyhmwFOu2rhmUAgVbnAbsJD8 uY9q9DH4/oxQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,302,1589266800"; d="scan'208";a="304071198" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.23]) by fmsmga004.fm.intel.com with ESMTP; 01 Jul 2020 18:50:52 -0700 From: "Huang\, Ying" To: David Rientjes Cc: Dave Hansen , Yang Shi , Dave Hansen , , , , Subject: Re: [RFC][PATCH 3/8] mm/vmscan: Attempt to migrate page in lieu of discard References: <20200629234503.749E5340@viggo.jf.intel.com> <20200629234509.8F89C4EF@viggo.jf.intel.com> <039a5704-4468-f662-d660-668071842ca3@linux.alibaba.com> <87h7urlioe.fsf@yhuang-dev.intel.com> <8182ede7-88ce-b891-d100-8c036130797e@intel.com> Date: Thu, 02 Jul 2020 09:50:51 +0800 In-Reply-To: (David Rientjes's message of "Wed, 1 Jul 2020 12:50:23 -0700") Message-ID: <87v9j6k7lw.fsf@yhuang-dev.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: 6B15B1801B5EA X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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: David Rientjes writes: > On Wed, 1 Jul 2020, Dave Hansen wrote: > >> Even if they don't allocate directly from PMEM, is it OK for such an app >> to get its cold data migrated to PMEM? That's a much more subtle >> question and I suspect the kernel isn't going to have a single answer >> for it. I suspect we'll need a cpuset-level knob to turn auto-demotion >> on or off. >> > > I think the answer is whether the app's cold data can be reclaimed, > otherwise migration to PMEM is likely better in terms of performance. So > any such app today should just be mlocking its cold data if it can't > handle overhead from reclaim? Yes. That's a way to solve the problem. A cpuset-level knob may be more flexible, because you don't need to change the application source code. Best Regards, Huang, Ying