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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 EC245C4360F for ; Thu, 28 Mar 2019 22:44:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5F1321855 for ; Thu, 28 Mar 2019 22:44:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553813078; bh=1GwTRB0RlvogRMsRHGKJps4BHsYdRaS42pr3urP5bgM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ZuAfqmUHjZO3w8i9oIUNR2ZvIQxX905Ex1non6BExGOydijyVmo3tgOkTLySWjM66 OTE/s0w6tzJblBHi+g8aLWze35o1ZYFYfp5rOfEwKag7FvDK6dnFMl8Vvw72Yq3psU v/koBKme5pSM/adKjoBBwWdQBG2Y4W4NBDxjN4+w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728053AbfC1Woh (ORCPT ); Thu, 28 Mar 2019 18:44:37 -0400 Received: from mga14.intel.com ([192.55.52.115]:22048 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727238AbfC1Woh (ORCPT ); Thu, 28 Mar 2019 18:44:37 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Mar 2019 15:44:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,282,1549958400"; d="scan'208";a="126781810" Received: from unknown (HELO localhost.localdomain) ([10.232.112.69]) by orsmga007.jf.intel.com with ESMTP; 28 Mar 2019 15:44:35 -0700 Date: Thu, 28 Mar 2019 16:45:50 -0600 From: Keith Busch To: Yang Shi Cc: "mhocko@suse.com" , "mgorman@techsingularity.net" , "riel@surriel.com" , "hannes@cmpxchg.org" , "akpm@linux-foundation.org" , "Hansen, Dave" , "Busch, Keith" , "Williams, Dan J" , "Wu, Fengguang" , "Du, Fan" , "Huang, Ying" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 06/10] mm: vmscan: demote anon DRAM pages to PMEM node Message-ID: <20190328224549.GA11100@localhost.localdomain> References: <1553316275-21985-1-git-send-email-yang.shi@linux.alibaba.com> <1553316275-21985-7-git-send-email-yang.shi@linux.alibaba.com> <20190324222040.GE31194@localhost.localdomain> <20190327003541.GE4328@localhost.localdomain> <39d8fb56-df60-9382-9b47-59081d823c3c@linux.alibaba.com> <20190327130822.GD7389@localhost.localdomain> <599849e6-05b6-1e4d-7578-5cf8825963d2@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <599849e6-05b6-1e4d-7578-5cf8825963d2@linux.alibaba.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 28, 2019 at 02:59:30PM -0700, Yang Shi wrote: > Yes, it still could fail. I can't tell which way is better for now. I > just thought scanning another round then migrating should be still > faster than swapping off the top of my head. I think it depends on the relative capacities between your primary and migration tiers and how it's used. Applications may allocate and pin directly out of pmem if they wish, so it's not a dedicated fallback memory space like swap.