Date: Fri, 13 Apr 2012 19:43:07 +0200 From: Florian Smeets <flo@FreeBSD.org> To: Alexander Best <arundel@FreeBSD.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@FreeBSD.org>, Mahesh Babu <maheshbabu90@yahoo.co.in> Subject: Re: Regarding core disable in FreeBSD 9 Message-ID: <4F8865AB.10504@FreeBSD.org> In-Reply-To: <20120413173440.GA48030@freebsd.org> References: <1334333913.65753.YahooMailNeo@web193204.mail.sg3.yahoo.com> <20120413173440.GA48030@freebsd.org>
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On 13.04.12 19:34, Alexander Best wrote: > On Sat Apr 14 12, Mahesh Babu wrote: >> How to disable a particular core in FreeBSD 9? >> How to enable it again? > > i don't think it's possible to do that in freebsd. what you can do is to > disable SMP oder hyperthreading. alternatively you can assign a certain process > to a certain core. > > i think there's a project to disable and enable specific cores on the fly. > freebsd is pretty far behind regarding this feature. beos was able to do this > anno 1998 or so afair. > You can set the following in /boot/loader.conf hint.lapic.128.disabled=1 hint.lapic.130.disabled=1 Where 128 and 130 are IDs of cores you want to disable, you can find the IDs for your CPUs/cores in dmesg or /var/log/messages e.g. cpu0 (BSP): APIC ID: 0 cpu1 (AP): APIC ID: 2 cpu2 (AP): APIC ID: 4 cpu3 (AP): APIC ID: 16 Enabling and disabling on the fly is not possible. Florian
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