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=-2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,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 41FABC04AB3 for ; Fri, 10 May 2019 16:36:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 09B902177B for ; Fri, 10 May 2019 16:36:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="aa7n+JxO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727762AbfEJQgV (ORCPT ); Fri, 10 May 2019 12:36:21 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:51372 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727496AbfEJQgV (ORCPT ); Fri, 10 May 2019 12:36:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=b/JhnmzdXvcZzBwouxXoQxGy1LUWG9vrwQ6s+nGq3oI=; b=aa7n+JxOP4GJyt+6e9t186rvV ZLNOAx0QcDgAMax2GMB3YAFR2nvjovRMNFHsqMoqrw7bksP5Q8t57AlEyhctFD8PzdKtfIZxNHlhk BrX2diNGkIneThNr0j/li+YDar0K9CwzwSzMjRNI7W+Txv4AWT/oCeGKEGoBxCafblJbgmvzstPVA 30TskXHyRLMWWBNBqfYi9PHfso3dkPLNR5XffHnIz7m43cbLaBTst9Kf/A9/zzwKrOG2FJqqc30DE YXtWqLHH6vgBfoqm12GBjjebNEbUh6DPDhKHlp48pY78sCZhOkd4aV3aHiXiSQcBrDo9Uyo4bZNRj uw3aSHlXQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hP8VJ-0007RN-1p; Fri, 10 May 2019 16:36:13 +0000 Date: Fri, 10 May 2019 09:36:12 -0700 From: Matthew Wilcox To: "Huang, Ying" Cc: Yang Shi , hannes@cmpxchg.org, mhocko@suse.com, mgorman@techsingularity.net, kirill.shutemov@linux.intel.com, hughd@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: vmscan: correct nr_reclaimed for THP Message-ID: <20190510163612.GA23417@bombadil.infradead.org> References: <1557447392-61607-1-git-send-email-yang.shi@linux.alibaba.com> <87y33fjbvr.fsf@yhuang-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87y33fjbvr.fsf@yhuang-dev.intel.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 10, 2019 at 10:12:40AM +0800, Huang, Ying wrote: > > + nr_reclaimed += (1 << compound_order(page)); > > How about to change this to > > > nr_reclaimed += hpage_nr_pages(page); Please don't. That embeds the knowledge that we can only swap out either normal pages or THP sized pages. I'm trying to make the VM capable of supporting arbitrary-order pages, and this would be just one more place to fix. I'm sympathetic to the "self documenting" argument. My current tree has a patch in it: mm: Introduce compound_nr Replace 1 << compound_order(page) with compound_nr(page). Minor improvements in readability. It goes along with this patch: mm: Introduce page_size() It's unnecessarily hard to find out the size of a potentially huge page. Replace 'PAGE_SIZE << compound_order(page)' with page_size(page). Better suggestions on naming gratefully received. I'm more happy with page_size() than I am with compound_nr(). page_nr() gives the wrong impression; page_count() isn't great either.