From owner-freebsd-hackers@FreeBSD.ORG Thu Mar 22 14:09:22 2012 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D161D1065678 for ; Thu, 22 Mar 2012 14:09:22 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from cyrus.watson.org (cyrus.watson.org [65.122.17.42]) by mx1.freebsd.org (Postfix) with ESMTP id A25938FC12 for ; Thu, 22 Mar 2012 14:09:22 +0000 (UTC) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [96.47.65.170]) by cyrus.watson.org (Postfix) with ESMTPSA id 5889646B2C; Thu, 22 Mar 2012 10:09:22 -0400 (EDT) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 9D652B940; Thu, 22 Mar 2012 10:09:21 -0400 (EDT) From: John Baldwin To: freebsd-hackers@freebsd.org Date: Thu, 22 Mar 2012 08:03:56 -0400 User-Agent: KMail/1.13.5 (FreeBSD/8.2-CBSD-20110714-p10; KDE/4.5.5; amd64; ; ) References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201203220803.57000.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Thu, 22 Mar 2012 10:09:21 -0400 (EDT) Cc: Mark Saad Subject: Re: Approaching the limit on PV entries X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 22 Mar 2012 14:09:22 -0000 On Wednesday, March 21, 2012 4:20:17 pm Mark Saad wrote: > On Wed, Mar 21, 2012 at 12:39 PM, Sergey Kandaurov wrote: > > On 21 March 2012 19:19, John Baldwin wrote: > >> On Tuesday, March 20, 2012 11:37:57 am Sergey Kandaurov wrote: > >>> On 22 November 2011 19:29, Mark Saad wrote: > >>> > Hello All > >>> > >>> [found this mail in my drafts, not sure if my answer is still useful] > >>> > >>> > I want to get to the bottom of a warning in dmesg. On 7.2-RELEASE and > >>> > 7.3-RELEASE I have seen the following warning in dmesg. > >>> > > >>> > Approaching the limit on PV entries, consider increasing either the > >>> > vm.pmap.shpgperproc or the vm.pmap.pv_entry_max sysctl. > >>> > > >>> > So looking around I see a few posts here and there about how to tune > >>> > the sysctls to address the warning however I am not 100% sure what > >>> > each value does. > >>> > It appears changing vm.pmap.shpgperproc affects the value of > >>> > vm.pmap.pv_entry_max . Can someone explain the relationship of the two > >>> > sysctls. Also > >>> > >>> This is how they are calculated. > >>> > >>> pv_entry_max = shpgperproc * maxproc + cnt.v_page_count; > >>> > >>> and, respectively, > >>> > >>> shpgperproc = (pv_entry_max - cnt.v_page_count) / maxproc; > >>> > >>> So, changing one sysctl will change another and vice versa. > >>> > >>> > what pitfalls of changing them are. > >>> > >>> Not known to me (on amd64 platform). > >>> I have had vm.pmap.shpgperproc=15000 on 8.1 amd64 with 4G RAM > >>> to make some badly written commercial software to work until it > >>> was decommissioned to the scrap. > >> > >> FYI, Alan just removed this warning and the associated sysctls from HEAD > >> yesterday because they were made obsolete several years ago. I think they are > >> obsolete even on 7. Certainly on 8. > > > > Yep, and since switching to direct map (somewhere around 7.x on amd64?) > > made PV entry limit factually obsolete, this is really cool. > > > > -- > > wbr, > > pluknet > > Interesting so this warning is relevant in 7.x ? No, looks like it was obsolete starting with 7.0. -- John Baldwin