From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752776AbcFGCUi (ORCPT ); Mon, 6 Jun 2016 22:20:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56967 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750886AbcFGCUg (ORCPT ); Mon, 6 Jun 2016 22:20:36 -0400 Message-ID: <1465266031.16365.153.camel@redhat.com> Subject: Re: [PATCH 06/10] mm: remove unnecessary use-once cache bias from LRU balancing From: Rik van Riel To: Johannes Weiner , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Mel Gorman , Andrea Arcangeli , Andi Kleen , Michal Hocko , Tim Chen , kernel-team@fb.com Date: Mon, 06 Jun 2016 22:20:31 -0400 In-Reply-To: <20160606194836.3624-7-hannes@cmpxchg.org> References: <20160606194836.3624-1-hannes@cmpxchg.org> <20160606194836.3624-7-hannes@cmpxchg.org> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-Hh3bOxqBqTybgtTa1zTW" Mime-Version: 1.0 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 07 Jun 2016 02:20:35 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-Hh3bOxqBqTybgtTa1zTW Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2016-06-06 at 15:48 -0400, Johannes Weiner wrote: > When the splitlru patches divided page cache and swap-backed pages > into separate LRU lists, the pressure balance between the lists was > biased to account for the fact that streaming IO can cause memory > pressure with a flood of pages that are used only once. New page > cache > additions would tip the balance toward the file LRU, and repeat > access > would neutralize that bias again. This ensured that page reclaim > would > always go for used-once cache first. >=20 > Since e9868505987a ("mm,vmscan: only evict file pages when we have > plenty"), page reclaim generally skips over swap-backed memory > entirely as long as there is used-once cache present, and will apply > the LRU balancing when only repeatedly accessed cache pages are left > - > at which point the previous use-once bias will have been neutralized. >=20 > This makes the use-once cache balancing bias unnecessary. Remove it. >=20 The code in get_scan_count() still seems to use the statistics of which you just removed the updating. What am I overlooking? --=20 All Rights Reversed. --=-Hh3bOxqBqTybgtTa1zTW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJXVi9wAAoJEM553pKExN6DK8MIALmRQa8GKIDg16qI26UguPKp KZlqTGGlTwLCX7EIf/HKx0xszSzmFGyM+s1kAQ+Gr+UqQHU+hbboQJraLJ73JNJk AYCXqzZn9GJ50gWCRbup/Bq1C9KVtRWv2ZEdbAkTKLnaoJqMs2x8Zq2jmP2ozzQv hiQMpCOuHqg/AVV1gJrrXcdKDApOZUrrzHqrJW7MayCwbv4797VqZj9b0EYwJx2w G63CnaTThpELN/2HzB+prWRntRlrnxxTQ4qr+EGDeViUc8LlihYJFTl2chcCbNmn ynWxSPs+yt4u1fq3g+7EGnWvHeGBif5XazREPZkxePtRg+VCE0GxWcQ5PrxxSAs= =svIi -----END PGP SIGNATURE----- --=-Hh3bOxqBqTybgtTa1zTW--