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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 C938FC2BB1D for ; Fri, 17 Apr 2020 04:06:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A32BE21D94 for ; Fri, 17 Apr 2020 04:06:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587096408; bh=Ox+92WObcJunp5pe05700XTqNPVCEcZ9XiB7PoMy0Tc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=fnBwAM2Zj4xLq2KLjmINBQAN1zXTygXtqrKSQP6CSgNf5oQI570hK6EOwban25A0X TNq4d46UA2QofCdszay4NjUHC/OeDjIX8kqVVELCfndkMU/835F1Ksux+IHohsXeMD /+rVMAELCoZD0RHyx9cd/Ov5UEwYLbdLlzmDKlaM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726400AbgDQEGr (ORCPT ); Fri, 17 Apr 2020 00:06:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:54606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725900AbgDQEGr (ORCPT ); Fri, 17 Apr 2020 00:06:47 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C772321D93; Fri, 17 Apr 2020 04:06:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587096407; bh=Ox+92WObcJunp5pe05700XTqNPVCEcZ9XiB7PoMy0Tc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=QY7ZU/+JVxuT2+vH/epQoI3Nw4QIVGsEgVwexZzpUIVeCl6hpubioHP9oR74gcb42 J1FpGvATJx+EGzI4rv2eMbjBISoyvIVfXOAaSaKV7uL+V6KcMVSBDwQMMtgCK4cJz1 AvgNYBimV4WNZVsQfXSLzqxwE6GXL3J2t/S1JbUI= Date: Thu, 16 Apr 2020 21:06:46 -0700 From: Andrew Morton To: "Huang\, Ying" Cc: Andrea Righi , Minchan Kim , Anchal Agarwal , , Subject: Re: [PATCH v3] mm: swap: properly update readahead statistics in unuse_pte_range() Message-Id: <20200416210646.774bae8c321e3a44d6ffa8c3@linux-foundation.org> In-Reply-To: <871romvmrh.fsf@yhuang-dev.intel.com> References: <20200416180132.GB3352@xps-13> <871romvmrh.fsf@yhuang-dev.intel.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > 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?