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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 384E7C433EF for ; Mon, 11 Jul 2022 21:51:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7972D6B0116; Mon, 11 Jul 2022 17:51:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7476E6B0117; Mon, 11 Jul 2022 17:51:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 610366B0118; Mon, 11 Jul 2022 17:51:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 5103B6B0116 for ; Mon, 11 Jul 2022 17:51:56 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 285E4616 for ; Mon, 11 Jul 2022 21:51:56 +0000 (UTC) X-FDA: 79676167032.01.0097932 Received: from mail-pj1-f43.google.com (mail-pj1-f43.google.com [209.85.216.43]) by imf17.hostedemail.com (Postfix) with ESMTP id B923840067 for ; Mon, 11 Jul 2022 21:51:55 +0000 (UTC) Received: by mail-pj1-f43.google.com with SMTP id cp18-20020a17090afb9200b001ef79e8484aso10447pjb.1 for ; Mon, 11 Jul 2022 14:51:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=p9WvUI7L8Lya8NVPrNOkTHA1J5fehorhhLCvTWLN6NQ=; b=LglQuGlonvYGPPZjabOXTGYJJ9xBnXC3UBTIQoxpI77p0NUX3w+SZG28aelAlL358K CwMwSh9EIhWXJ66UMrZDlIch6as7McW6bKk2RP0UqxcsWMXQd4X1xInQu3YI31jCoE3P aqWxz0Ty8o1+KbwgV+lK5ZH6IsZK0ydgNa0ObtmGg8k2VkCtuEIdkzI9YoggFZpAoi+o juZkgcEqBBNhkBKgrTYCOCjiCrskOqCqlK1YyoKAK6rYrPtt8iLUZVkedpt2+JFldny0 zjO1U+7bwHw0HN7mQnP2/N2jrH5R+QoEalrOwKrZhyuayYJkho3R/InxjPaMKiLDQUFT Ddkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=p9WvUI7L8Lya8NVPrNOkTHA1J5fehorhhLCvTWLN6NQ=; b=Rgeq1UZhMaiKwriBPBeTT9yxYO/aTnG826J3psL2wSVq8q4p8MWkZ4lbtjned+PQii a5E+VOxnb56LwzN5c+pKZK67J0XM3/RABVVUMGCpjKTLy2pONPdH+I5JahG9e/NXo15l 4/xkyPYPrbDO9fk5PykHe7XE8mSWN+uwCJjLr9WIgfgVGWHG9ETj0gKspAbamaRKotIL YEe5LlkKIQuuk25MacGGlDjb3RNSYsrNSCrLZsRel+/vhoDwJ8MpzwK4aaR27g7nACah guiET3CzkBOUY25Bj1zWg5xU36skVzTWJ4Dctu1iJqLZUsMcHT4qcwDZt7U1WtL47xb5 BAsg== X-Gm-Message-State: AJIora/nlIgkTncLWuiBYyIpBJtoK8Nnngmu0Dikml7+xpCByQFIOvnC 38aCtWrMEkNLTuklXvS7OkDEMo0qJ1Zo38iYDto= X-Google-Smtp-Source: AGRyM1vDUQE6hZ8HS4qKJhbOcFrEUy3QLeUmMGjD+AEbKLmQ6nE0NXerHaf951TIVpvm8QIjhXJl9cov/EGdoKz2nDI= X-Received: by 2002:a17:90b:4c48:b0:1ef:ff05:99f5 with SMTP id np8-20020a17090b4c4800b001efff0599f5mr491489pjb.21.1657576314702; Mon, 11 Jul 2022 14:51:54 -0700 (PDT) MIME-Version: 1.0 References: <20220706235936.2197195-1-zokeefe@google.com> <20220706235936.2197195-4-zokeefe@google.com> <20220708140119.6da1413a413214bc603423e3@linux-foundation.org> In-Reply-To: From: Yang Shi Date: Mon, 11 Jul 2022 14:51:42 -0700 Message-ID: Subject: Re: [mm-unstable v7 03/18] mm/khugepaged: add struct collapse_control To: "Zach O'Keefe" Cc: Andrew Morton , Alex Shi , David Hildenbrand , David Rientjes , Matthew Wilcox , Michal Hocko , Pasha Tatashin , Peter Xu , Rongwei Wang , SeongJae Park , Song Liu , Vlastimil Babka , Zi Yan , Linux MM , Andrea Arcangeli , Arnd Bergmann , Axel Rasmussen , Chris Kennelly , Chris Zankel , Helge Deller , Hugh Dickins , Ivan Kokshaysky , "James E.J. Bottomley" , Jens Axboe , "Kirill A. Shutemov" , Matt Turner , Max Filippov , Miaohe Lin , Minchan Kim , Patrick Xia , Pavel Begunkov , Thomas Bogendoerfer Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657576315; a=rsa-sha256; cv=none; b=hAx3/41mJXEnJthzzqSwpau4cbCsZCJI9JxXf4X+AzZ5mSwr6QjO1NclFRCJeg5oBellBy tQ8aCGS/y6QYod9lSHkwPxH8hRT0o2PgQ7iGJ5YxU+8x57UtWLaC7W7l4PdT6Rr7jz1jK3 5iPR8xfHGhmiZ7zEP2KUsfXUYVt9hnk= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=LglQuGlo; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf17.hostedemail.com: domain of shy828301@gmail.com designates 209.85.216.43 as permitted sender) smtp.mailfrom=shy828301@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657576315; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=p9WvUI7L8Lya8NVPrNOkTHA1J5fehorhhLCvTWLN6NQ=; b=iBI+dXWeDMMRXgMeW0GlO9Frpns/2EdRYvI7h9RZPw90f9lnl90n+mfP9VpkGtSRhDYe+Z yHLMrk9smtXs/4MzJvEo/ofXnR4RCHBEaRAQHU3Jnh6/tjSFjxn4+bYXp8duP3o8Fm/wrK dykqHNpBipbVgAcvioSs9VSkSSUx5SE= Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=LglQuGlo; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf17.hostedemail.com: domain of shy828301@gmail.com designates 209.85.216.43 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-Stat-Signature: 4bjxctqx5iy61rzpg5as3bwgfkrpr5qj X-Rspamd-Queue-Id: B923840067 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1657576315-887780 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 Mon, Jul 11, 2022 at 11:29 AM Zach O'Keefe wrote: > > On Fri, Jul 8, 2022 at 2:01 PM Andrew Morton wrote: > > > > On Wed, 6 Jul 2022 16:59:21 -0700 "Zach O'Keefe" wrote: > > > > > Modularize hugepage collapse by introducing struct collapse_control. > > > This structure serves to describe the properties of the requested > > > collapse, as well as serve as a local scratch pad to use during the > > > collapse itself. > > > > > > Start by moving global per-node khugepaged statistics into this > > > new structure. Note that this structure is still statically allocated > > > since CONFIG_NODES_SHIFT might be arbitrary large, and stack-allocating > > > a MAX_NUMNODES-sized array could cause -Wframe-large-than= errors. > > > > > > Signed-off-by: Zach O'Keefe > > > --- > > > mm/khugepaged.c | 87 ++++++++++++++++++++++++++++--------------------- > > > 1 file changed, 50 insertions(+), 37 deletions(-) > > > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > > index 196eaadbf415..f1ef02d9fe07 100644 > > > --- a/mm/khugepaged.c > > > +++ b/mm/khugepaged.c > > > @@ -85,6 +85,14 @@ static struct kmem_cache *mm_slot_cache __read_mostly; > > > > > > #define MAX_PTE_MAPPED_THP 8 > > > > > > +struct collapse_control { > > > + /* Num pages scanned per node */ > > > + int node_load[MAX_NUMNODES]; > > > > Does this actually need to be 32-bit? Looking at the current code I'm > > suspecting that khugepaged_node_load[] could be a ushort? > > > > [And unsigned int would be more appropriate, but we always do that :(] > > > > Hey Andrew, > > Thanks for taking the time to review, and good catch - I don't think > we need 32 bits. > > Minimally, we just need to be able to hold the maximum value of > HPAGE_PMD_NR = 1 << (PMD_SHIFT - PAGE_SHIFT). > > I'm not sure what arch/config options (that also use THP) produce the > minimum/maximum value here. I looked through most of the archs that > define PMD_SHIFT, and couldn't find an example where we'd need > 16 > bits, with most cases still requiring > 8 bits. All the various > configs do get complicated though. > > Is it acceptable to use u16, with an #error if HPAGE_PMD_ORDER >= 16? Fine to me. > > Thanks, > Zach