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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 A0502ECE58E for ; Thu, 17 Oct 2019 16:39:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5D03521848 for ; Thu, 17 Oct 2019 16:39:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="L5dLzOre" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5D03521848 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D029C8E000A; Thu, 17 Oct 2019 12:39:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CB2DF8E0003; Thu, 17 Oct 2019 12:39:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC7FF8E000A; Thu, 17 Oct 2019 12:39:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0188.hostedemail.com [216.40.44.188]) by kanga.kvack.org (Postfix) with ESMTP id 960BF8E0003 for ; Thu, 17 Oct 2019 12:39:18 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 3046C1802FA29 for ; Thu, 17 Oct 2019 16:39:18 +0000 (UTC) X-FDA: 76053836796.01.idea02_3411ec58a245e X-HE-Tag: idea02_3411ec58a245e X-Filterd-Recvd-Size: 4327 Received: from mail-yb1-f193.google.com (mail-yb1-f193.google.com [209.85.219.193]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Thu, 17 Oct 2019 16:39:17 +0000 (UTC) Received: by mail-yb1-f193.google.com with SMTP id q143so889863ybg.12 for ; Thu, 17 Oct 2019 09:39:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=vYJvPdDl3T7Fx646ASlNZBmczwkC7H3BSoulK6E2T3I=; b=L5dLzOreODZtz1fC6R658TQwqBXto0USF2KYsRzaAvcvOCiUwEbkp6P5PvMEs44M0I JCSKtrJl55eSbC8ndDhVh1NmUSrMQcOPQC543hljZtgROp448B88vZ2/yI0ib41HDDoK tPRnGmmoUIDibih651Fnt9rTGmwhv0x04fS6a5ZbMMukW+VYWAupBqC6dOPguuX0K0CD SA44uo2bDMlXVm1hKuv7Lp1uvGn9L0pQ2IHRPUzTR834W1SQBDSAy4N+e2/Xt51BDfuT HYShlFdUAiLrpHDbm8LESk4Xx2PIcuL5hLAXPkErrcCvAqxO5ArsXdEbfOiDehwjcJvC 6KJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vYJvPdDl3T7Fx646ASlNZBmczwkC7H3BSoulK6E2T3I=; b=Lzp5Mx9wkSCNwyINZ3CYkbMiE/OOEY2/26/mAcMhrL1COnNIXuZ+Gpj7C9dKXv7C4o 8OBzfaZzGZV9R1LCjdXsuUGHlQohzYmop+uHqIyQ+tN9tC0gSKHqQz/m3R/DI3IwEoE4 owGMlIuCGfHaA0AxbokiIg/OJaRy8LiQtDuaEBdzuPdE2CruR8L0QulC5YWBr+RP256i qKFPKoTOFhdl3ScxykF/o+Snjbb9JTRFKyPWur0jUcQIVsibmB4VG6bHwqbOSSrOYp7s dj0mzBokvY/4fmAoDEpIaQHfXUmehmLrKuX9e1KI9xn+e/jR9HV6sncgUo+xjOimjT8a aqUA== X-Gm-Message-State: APjAAAUChhag2OY6VCdEpAZKp3MR3ZM7GPciz2Xhi/qf+2xPCe/Si+Xd z31gLIuR6cUfhRvy4PgKI64gpqM/6dubnX72v4xsaQ== X-Google-Smtp-Source: APXvYqxdYvRwKra9r9/E+OOqWK7PsmcGav4kYCUYznmop5C9tp4Z3WcERTqCA2rhAHcIwWJPWLpbrclmbwc5zuy3oDY= X-Received: by 2002:a25:4292:: with SMTP id p140mr2700421yba.147.1571330356542; Thu, 17 Oct 2019 09:39:16 -0700 (PDT) MIME-Version: 1.0 References: <20191016221148.F9CCD155@viggo.jf.intel.com> <85512332-d9d4-6a72-0b42-a8523abc1b5f@intel.com> In-Reply-To: <85512332-d9d4-6a72-0b42-a8523abc1b5f@intel.com> From: Shakeel Butt Date: Thu, 17 Oct 2019 09:39:04 -0700 Message-ID: Subject: Re: [PATCH 0/4] [RFC] Migrate Pages in lieu of discard To: Dave Hansen Cc: Suleiman Souhlal , Dave Hansen , Linux Kernel , Linux MM , Dan Williams Content-Type: text/plain; charset="UTF-8" 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 Thu, Oct 17, 2019 at 9:32 AM Dave Hansen wrote: > > On 10/17/19 9:01 AM, Suleiman Souhlal wrote: > > One problem that came up is that if you get into direct reclaim, > > because persistent memory can have pretty low write throughput, you > > can end up stalling users for a pretty long time while migrating > > pages. > > Basically, you're saying that memory load spikes turn into latency spikes? > > FWIW, we have been benchmarking this sucker with benchmarks that claim > to care about latency. In general, compared to DRAM, we do see worse > latency, but nothing catastrophic yet. I'd be interested if you have > any workloads that act as reasonable proxies for your latency requirements. > > > Because of that, we moved to a solution based on the proactive reclaim > > of idle pages, that was presented at LSFMM earlier this year: > > https://lwn.net/Articles/787611/ . > > I saw the presentation. The feedback in the room as I remember it was > that proactive reclaim essentially replaced the existing reclaim > mechanism, to which the audience was not receptive. Have folks opinions > changed on that, or are you looking for other solutions? > I am currently working on a solution which shares the mechanisms between regular and proactive reclaim. The interested users/admins can setup proactive reclaim otherwise the regular reclaim will work on low memory. I will have something in one/two months and will post the patches. Shakeel