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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9FF0BC2D0EF for ; Fri, 17 Apr 2020 05:18:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5464E2076D for ; Fri, 17 Apr 2020 05:18:43 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5464E2076D 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 B662E8E0003; Fri, 17 Apr 2020 01:18:42 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B18428E0001; Fri, 17 Apr 2020 01:18:42 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A2E698E0003; Fri, 17 Apr 2020 01:18:42 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0200.hostedemail.com [216.40.44.200]) by kanga.kvack.org (Postfix) with ESMTP id 884EA8E0001 for ; Fri, 17 Apr 2020 01:18:42 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 45C1F824556B for ; Fri, 17 Apr 2020 05:18:42 +0000 (UTC) X-FDA: 76716192084.28.legs09_69086e237d321 X-HE-Tag: legs09_69086e237d321 X-Filterd-Recvd-Size: 3248 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf37.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Apr 2020 05:18:41 +0000 (UTC) IronPort-SDR: fJvSVX/hDr9lb9UG6r8b5/v3XnQfLQhY2fXqAZi/IlSLgHysRYe+K0x7IOzh1qUrZXKYDYAJRH 8mm/WVMk3Fug== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Apr 2020 22:18:39 -0700 IronPort-SDR: +8q+macfzoj/N2yw0IIxmAGyRLpsfCjBnl+JlEA8LbLjUnvsb5Yf0/G791k12W+LlekB2AY143 QV1s76f9+Z8A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,393,1580803200"; d="scan'208";a="454603579" Received: from yhuang-dev.sh.intel.com (HELO yhuang-dev) ([10.239.159.23]) by fmsmga005.fm.intel.com with ESMTP; 16 Apr 2020 22:18:38 -0700 From: "Huang\, Ying" To: Andrew Morton Cc: Andrea Righi , Minchan Kim , Anchal Agarwal , , Subject: Re: [PATCH v3] mm: swap: properly update readahead statistics in unuse_pte_range() References: <20200416180132.GB3352@xps-13> <871romvmrh.fsf@yhuang-dev.intel.com> <20200416210646.774bae8c321e3a44d6ffa8c3@linux-foundation.org> Date: Fri, 17 Apr 2020 13:18:37 +0800 In-Reply-To: <20200416210646.774bae8c321e3a44d6ffa8c3@linux-foundation.org> (Andrew Morton's message of "Thu, 16 Apr 2020 21:06:46 -0700") Message-ID: <87sgh2u1ua.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-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: Andrew Morton writes: > On Fri, 17 Apr 2020 11:01:22 +0800 "Huang\, Ying" wrote: > >> Andrea Righi writes: >> >> > In unuse_pte_range() we blindly swap-in pages without checking if the >> > swap entry is already present in the swap cache. >> > >> > By doing this, the hit/miss ratio used by the swap readahead heuristic >> > is not properly updated and this leads to non-optimal performance during >> > swapoff. >> >> It's more important to describe why we need this patch in the patch >> description. So, please add some information about your use case. And >> please focus on the technical part instead of the business part. > > Confused. I thought the changelog was quite good. If "business part" > means "end user effect of the patch" then that's a very important > thing. Previously, Andrea has described their use case in the cloud environment to hiberate the guest and swapoff after resuming. So swapoff performance is important for them. I think that should be included. For the business part, I mean something like "Ubuntu used in AWS EC2", I think that isn't important for the patch description. >> Thanks! But you don't need to do this. You can add my Reviewed-by after >> we have finished the work on patch description. > > Can you be more specific about how you want this changed? Please use Reviewed-by: "Huang, Ying" Best Regards, Huang, Ying