Date: Thu, 22 Mar 2012 13:48:29 -0400 From: Mark Saad <nonesuch@longcount.org> To: freebsd-hackers@freebsd.org Subject: Re: Approaching the limit on PV entries Message-ID: <CAMXt9NbY9Opz6r2JpLrOGEZ3nU3amc5-5xLcKA0CyFq19mMZBg@mail.gmail.com> In-Reply-To: <201203220803.57000.jhb@freebsd.org> References: <CAMXt9NapczKEmBU3Wwwh99jb6Vv9bhejxgpmVqStGBwvP7BmAA@mail.gmail.com> <CAE-mSOJw1wo9SqtfDfH9Qn30cUKyuiB1aTTwqdQU7-5iDrFdPg@mail.gmail.com> <CAMXt9NZbn8OAvRQVvYSi8c2N2ajfASjDnXDwyXqKsFr9B%2BJOtA@mail.gmail.com> <201203220803.57000.jhb@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Thu, Mar 22, 2012 at 8:03 AM, John Baldwin <jhb@freebsd.org> wrote: > On Wednesday, March 21, 2012 4:20:17 pm Mark Saad wrote: >> On Wed, Mar 21, 2012 at 12:39 PM, Sergey Kandaurov <pluknet@gmail.com> w= rote: >> > On 21 March 2012 19:19, John Baldwin <jhb@freebsd.org> wrote: >> >> On Tuesday, March 20, 2012 11:37:57 am Sergey Kandaurov wrote: >> >>> On 22 November 2011 19:29, Mark Saad <nonesuch@longcount.org> wrote: >> >>> > Hello All >> >>> >> >>> [found this mail in my drafts, not sure if my answer is still useful= ] >> >>> >> >>> > =C2=A0I want to get to the bottom of a warning in dmesg. On 7.2-RE= LEASE and >> >>> > 7.3-RELEASE I have seen the following warning in dmesg. >> >>> > >> >>> > Approaching the limit on PV entries, consider increasing either th= e >> >>> > 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 tu= ne >> >>> > 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 =3D shpgperproc * maxproc + cnt.v_page_count; >> >>> >> >>> and, respectively, >> >>> >> >>> shpgperproc =3D (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=3D15000 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 H= EAD >> >> yesterday because they were made obsolete several years ago. =C2=A0I = think they are >> >> obsolete even on 7. =C2=A0Certainly 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 Any chance it could be mfc'ed to 7-STABLE ? --=20 mark saad | nonesuch@longcount.org
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAMXt9NbY9Opz6r2JpLrOGEZ3nU3amc5-5xLcKA0CyFq19mMZBg>