From patchwork Wed Jun 24 16:49:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Savitz X-Patchwork-Id: 11623777 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 0A48F92A for ; Wed, 24 Jun 2020 16:52:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CC9FE2073E for ; Wed, 24 Jun 2020 16:52:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="C3Aq1EOx" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CC9FE2073E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1DE576B0010; Wed, 24 Jun 2020 12:52:33 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 168266B0022; Wed, 24 Jun 2020 12:52:33 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 030F76B0023; Wed, 24 Jun 2020 12:52:32 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0194.hostedemail.com [216.40.44.194]) by kanga.kvack.org (Postfix) with ESMTP id DC3D06B0010 for ; Wed, 24 Jun 2020 12:52:32 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6DAF5181AC9C6 for ; Wed, 24 Jun 2020 16:52:32 +0000 (UTC) X-FDA: 76964698944.15.rain11_0a02aae26e45 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin15.hostedemail.com (Postfix) with ESMTP id 094141814B0CC for ; Wed, 24 Jun 2020 16:52:27 +0000 (UTC) X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,jsavitz@redhat.com,,RULES_HIT:30034:30051:30054:30064,0,RBL:207.211.31.120:@redhat.com:.lbl8.mailshell.net-62.18.0.100 66.10.201.10;04yfdbwzsmjo9j6cgfrhbrceffezwoc1stdye7exz83thnkxajkgaypyx4tee5k.giio95xcuxtz34pjmtfz817myqyq849qxpdcesrcbs6o53zgw6awzzzjbou5izs.h-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:ft,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:26,LUA_SUMMARY:none X-HE-Tag: rain11_0a02aae26e45 X-Filterd-Recvd-Size: 4211 Received: from us-smtp-1.mimecast.com (us-smtp-delivery-1.mimecast.com [207.211.31.120]) by imf40.hostedemail.com (Postfix) with ESMTP for ; Wed, 24 Jun 2020 16:52:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593017546; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=YgOG3Qn9UrbkC82Csvd2S1YBbX7wsXZhXBrd7kB7GaE=; b=C3Aq1EOxuQXfzCxHMRimNJ+GXjogDz2LvE7uonKeZwnQqWLNMMHAX240bo06L360qLJeia Jwk+i62GJ9eAnMeMb6grGCoAwCgKEGzplRcDWuIMUUH4W6CSnuSZFLUcOcva+7RkFK/1BO NtL/Pd57oecoq0dB17BNYgTunDsYClw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-299-9XDBz30yN5y-jP_osSf3Ow-1; Wed, 24 Jun 2020 12:52:24 -0400 X-MC-Unique: 9XDBz30yN5y-jP_osSf3Ow-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AE81A107ACF4; Wed, 24 Jun 2020 16:52:22 +0000 (UTC) Received: from jsavitz.bos.com (ovpn-112-219.rdu2.redhat.com [10.10.112.219]) by smtp.corp.redhat.com (Postfix) with ESMTP id C8C552B4AB; Wed, 24 Jun 2020 16:52:18 +0000 (UTC) From: Joel Savitz To: linux-kernel@vger.kernel.org Cc: Joel Savitz , Vlastimil Babka , John Hubbard , Andrew Morton , Rafael Aquini , Fabrizio D'Angelo , linux-mm@kvack.org Subject: [PATCH v2] mm/page_alloc: fix documentation error and remove magic numbers Date: Wed, 24 Jun 2020 12:49:43 -0400 Message-Id: <20200624164943.32048-1-jsavitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Rspamd-Queue-Id: 094141814B0CC X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000063, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When I increased the upper bound of the min_free_kbytes value in ee8eb9a5fe863, I forgot to tweak the above comment to reflect the new value. This patch fixes that mistake. In addition, this patch replaces the magic number bounds with symbolic constants to clarify the logic. changes from v1: - declare constants via enum instead of separate integers Suggested-by: John Hubbard Suggested-by: Vlastimil Babka Signed-off-by: Joel Savitz --- mm/page_alloc.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 48eb0f1410d4..733c81678b0e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7832,7 +7832,7 @@ void setup_per_zone_wmarks(void) * Initialise min_free_kbytes. * * For small machines we want it small (128k min). For large machines - * we want it large (64MB max). But it is not linear, because network + * we want it large (256MB max). But it is not linear, because network * bandwidth does not increase linearly with machine size. We use * * min_free_kbytes = 4 * sqrt(lowmem_kbytes), for better accuracy: @@ -7852,6 +7852,8 @@ void setup_per_zone_wmarks(void) * 8192MB: 11584k * 16384MB: 16384k */ +static enum { MIN_FREE_KBYTES_LOWER_BOUND = 1 << 7, MIN_FREE_KBYTES_UPPER_BOUND = 1 << 18 }; + int __meminit init_per_zone_wmark_min(void) { unsigned long lowmem_kbytes; @@ -7862,10 +7864,10 @@ int __meminit init_per_zone_wmark_min(void) if (new_min_free_kbytes > user_min_free_kbytes) { min_free_kbytes = new_min_free_kbytes; - if (min_free_kbytes < 128) - min_free_kbytes = 128; - if (min_free_kbytes > 262144) - min_free_kbytes = 262144; + if (min_free_kbytes < MIN_FREE_KBYTES_LOWER_BOUND) + min_free_kbytes = MIN_FREE_KBYTES_LOWER_BOUND; + if (min_free_kbytes > MIN_FREE_KBYTES_UPPER_BOUND) + min_free_kbytes = MIN_FREE_KBYTES_UPPER_BOUND; } else { pr_warn("min_free_kbytes is not updated to %d because user defined value %d is preferred\n", new_min_free_kbytes, user_min_free_kbytes);