From owner-freebsd-hackers@FreeBSD.ORG Wed Mar 21 16:17:37 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 B62C2106564A for ; Wed, 21 Mar 2012 16:17:37 +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 6DBB58FC29 for ; Wed, 21 Mar 2012 16:17:37 +0000 (UTC) Received: from bigwig.baldwin.cx (bigwig.baldwin.cx [96.47.65.170]) by cyrus.watson.org (Postfix) with ESMTPSA id 247C346B0D; Wed, 21 Mar 2012 12:17:37 -0400 (EDT) Received: from jhbbsd.localnet (unknown [209.249.190.124]) by bigwig.baldwin.cx (Postfix) with ESMTPSA id 87B21B960; Wed, 21 Mar 2012 12:17:36 -0400 (EDT) From: John Baldwin To: freebsd-hackers@freebsd.org Date: Wed, 21 Mar 2012 11:19:42 -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="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201203211119.43022.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (bigwig.baldwin.cx); Wed, 21 Mar 2012 12:17:36 -0400 (EDT) Cc: Mark Saad , Sergey Kandaurov 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: Wed, 21 Mar 2012 16:17:37 -0000 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. -- John Baldwin