Date: Fri, 30 Nov 2007 16:21:14 +0100 From: "Claus Guttesen" <kometen@gmail.com> To: "Pete French" <petefrench@ticketswitch.com> Cc: max@love2party.net, kris@freebsd.org, freebsd-stable@freebsd.org Subject: Re: Also seeing 2 x quad-core system slower that 2 x dual core Message-ID: <b41c75520711300721w417b0c39ld9e32a10ee5251c1@mail.gmail.com> In-Reply-To: <E1Iy47z-0001f0-QX@dilbert.ticketswitch.com> References: <474FD17D.7080209@FreeBSD.org> <E1Iy47z-0001f0-QX@dilbert.ticketswitch.com>
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> > Yes, if the claim is that the hardware is absolutely identical apart > > from one having two quad-core CPUs instead of two dual-core, the next > > step is to disable half of the CPUs and confirm that the problem goes away. > > Just comming back to this today, will do a side by side compare of the dmesg > later to make sure that they *are* identical as claimed, but the idea of > disabling half the CPU's is an excellent one! > > Aha, brilliant idea! > > > Check dmesg for the APIC numbers corresponding to the CPUs you want to > > disable and add the corresponding entries to /boot/loader.conf, e.g.: > > You mean this bit? > > FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs > cpu0 (BSP): APIC ID: 0 > cpu1 (AP): APIC ID: 1 > cpu2 (AP): APIC ID: 2 > cpu3 (AP): APIC ID: 3 > cpu4 (AP): APIC ID: 4 > cpu5 (AP): APIC ID: 5 > cpu6 (AP): APIC ID: 6 > cpu7 (AP): APIC ID: 7 For completeness sake :-) you could try to disable the second quad-core-cpu completely rather than 2 cores on each unit and redo the test. -- regards Claus When lenity and cruelty play for a kingdom, the gentlest gamester is the soonest winner. Shakespeare
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