Re: Force 1 CPU on SMP kernel?
On Mon, Jan 27, 2003 at 11:33:02PM -0500, Adam Migus wrote: Hi, I'm doing some performance analysis on FreeBSD. I would like to be able to make an SMP kernel use only one CPU. Of course I realize running GENERIC would only use 1 CPU but the concern is that the overhead assoicated with SMP will skew the statistics. So my question is what would be the 'best' way to make an SMP kernel only start/use CPU0? Yank the others ? Ceri -- Happiness is having a scratch for every itch. -- Ogden Nash To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
* Ceri Davies [EMAIL PROTECTED] [20030128 12:50]: wrote: On Mon, Jan 27, 2003 at 11:33:02PM -0500, Adam Migus wrote: Hi, I'm doing some performance analysis on FreeBSD. I would like to be able to make an SMP kernel use only one CPU. Of course I realize running GENERIC would only use 1 CPU but the concern is that the overhead assoicated with SMP will skew the statistics. So my question is what would be the 'best' way to make an SMP kernel only start/use CPU0? Yank the others ? What about building two kernels, one SMP, the other non-SMP, then just boot wheichever kernel you want? Doesn't it server same purpose? Better than Ceri's idea ;) -Wash -- Odhiambo Washington [EMAIL PROTECTED] The box said 'Requires Wananchi Online Ltd. www.wananchi.com Windows 95, NT, or better,' Tel: +254 2 313985-9 +254 2 313922 so I installed FreeBSD. GSM: +254 72 743223 +254 733 744121 This sig is McQ! :-) I'd love to go out with you, but I'm converting my calendar watch from Julian to Gregorian. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
On Tue, Jan 28, 2003 at 12:53:49PM +0300, Odhiambo Washington wrote: that the overhead assoicated with SMP will skew the statistics. So my question is what would be the 'best' way to make an SMP kernel only start/use CPU0? Yank the others ? What about building two kernels, one SMP, the other non-SMP, then just boot wheichever kernel you want? Doesn't it server same purpose? Better than Ceri's idea ;) -Wash Unless I read him wrong, but I think he wants a SMP kernel to run on a single CPU. Besides pulling the thing out of the box, is it possible to disable one of them via BIOS? Jiawei Ye -- Without the userland, the kernel is useless. --inspired by The Tao of Programming To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
* De: Odhiambo Washington [EMAIL PROTECTED] [ Data: 2003-01-28 ] [ Subjecte: Re: Force 1 CPU on SMP kernel? ] * Ceri Davies [EMAIL PROTECTED] [20030128 12:50]: wrote: On Mon, Jan 27, 2003 at 11:33:02PM -0500, Adam Migus wrote: Hi, I'm doing some performance analysis on FreeBSD. I would like to be able to make an SMP kernel use only one CPU. Of course I realize running GENERIC would only use 1 CPU but the concern is that the overhead assoicated with SMP will skew the statistics. So my question is what would be the 'best' way to make an SMP kernel only start/use CPU0? Yank the others ? What about building two kernels, one SMP, the other non-SMP, then just boot wheichever kernel you want? Doesn't it server same purpose? Better than Ceri's idea ;) You're missing the point. He wants to boot only the bootstrap processor, none of the APs, but still be running an SMP kernel. I think checking how much overhead SMP and APIC_IO add is a noble goal, and throwing real SMP into the mix would be dumb. -- Juli Mallett [EMAIL PROTECTED] AIM: BSDFlata -- IRC: juli on EFnet OpenDarwin, Mono, FreeBSD Developer ircd-hybrid Developer, EFnet addict FreeBSD on MIPS-Anything on FreeBSD To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
quote who=Juli Mallett * De: Odhiambo Washington [EMAIL PROTECTED] [ Data: 2003-01-28 ] [ Subjecte: Re: Force 1 CPU on SMP kernel? ] * Ceri Davies [EMAIL PROTECTED] [20030128 12:50]: wrote: On Mon, Jan 27, 2003 at 11:33:02PM -0500, Adam Migus wrote: Hi, I'm doing some performance analysis on FreeBSD. I would like to be able to make an SMP kernel use only one CPU. Of course I realize running GENERIC would only use 1 CPU but the concern is that the overhead assoicated with SMP will skew the statistics. So my question is what would be the 'best' way to make an SMP kernel only start/use CPU0? Yank the others ? What about building two kernels, one SMP, the other non-SMP, then just boot wheichever kernel you want? Doesn't it server same purpose? Better than Ceri's idea ;) You're missing the point. He wants to boot only the bootstrap processor, none of the APs, but still be running an SMP kernel. I think checking how much overhead SMP and APIC_IO add is a noble goal, and throwing real SMP into the mix would be dumb. Yes, just to be more explicit. What I want to do is get the 'real' difference a second processor makes. ie. If I run GENERIC I'm not incurring the overhead associated with SMP/APIC. I want to use the same kernel making as small a change as nessessary to have the machine start/use just one CPU. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
On Tue, 28 Jan 2003, Adam Migus wrote: Yes, just to be more explicit. What I want to do is get the 'real' difference a second processor makes. ie. If I run GENERIC I'm not incurring the overhead associated with SMP/APIC. I want to use the same kernel making as small a change as nessessary to have the machine start/use just one CPU. I'm not aware of any hacks to disable APs through loader.conf. If you're trying to benchmark the system's performance with 1 vs N CPUs, you're best off pulling all but the BSP CPU out of the machine. For such a benchmark to be accurate, you shouldn't make any software changes (kernel, daemons or startup configs). Regards, Andre Guibert de Bruet | Enterprise Software Consultant Silicon Landmark, LLC. | http://siliconlandmark.com/ To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
Hi, Does FreeBSD-SMP have anything equivalent to the processor_bind(2) call on Solaris, which binds a process to a specific processor? http://docs.sun.com/db/doc/816-0212/6m6nd4nci?a=view -- Craig Rodrigues http://home.attbi.com/~rodrigc [EMAIL PROTECTED] To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
On Tue, Jan 28, 2003 at 12:33:32PM -0500, Andre Guibert de Bruet wrote: On Tue, 28 Jan 2003, Adam Migus wrote: Yes, just to be more explicit. What I want to do is get the 'real' difference a second processor makes. ie. If I run GENERIC I'm not incurring the overhead associated with SMP/APIC. I want to use the same kernel making as small a change as nessessary to have the machine start/use just one CPU. I'm not aware of any hacks to disable APs through loader.conf. If you're trying to benchmark the system's performance with 1 vs N CPUs, you're best off pulling all but the BSP CPU out of the machine. For such a benchmark to be accurate, you shouldn't make any software changes (kernel, daemons or startup configs). VOlunteers to implement psradm maybe? W/ -- | / o / /_ _ [EMAIL PROTECTED] |/|/ / / /( (_) Bulte To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
Re: Force 1 CPU on SMP kernel?
quote who=Andre Guibert de Bruet On Tue, 28 Jan 2003, Adam Migus wrote: Yes, just to be more explicit. What I want to do is get the 'real' difference a second processor makes. ie. If I run GENERIC I'm not incurring the overhead associated with SMP/APIC. I want to use the same kernel making as small a change as nessessary to have the machine start/use just one CPU. I'm not aware of any hacks to disable APs through loader.conf. If you're trying to benchmark the system's performance with 1 vs N CPUs, you're best off pulling all but the BSP CPU out of the machine. For such a benchmark to be accurate, you shouldn't make any software changes (kernel, daemons or startup configs). I tend to agree but things like warrenties and flakey boards preclude removal of CPU(s). All the same I think the ability to turn on/off AP's at boot would be useful in general. -- Adam Migus - Research Scientist Network Associates Laboratories (http://www.nailabs.com) TrustedBSD (http://www.trustedbsd.org) FreeBSD (http://www.freebsd.org) To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-current in the body of the message
