Re: Detecting SMP
On Tue, 20 Feb 2001, Burton Windle wrote:
>Hello. Is there a way, when running a non-SMP kernel, to detect or
>otherwise tell (software only; the machine is 2400 miles away) if the
>system has SMP capibilties? Would /proc/cpuinfo show two CPUs if the
>kernel is non-SMP? Thanks!
>
>(btw, the kernel in question is a stock RH6.2 kernel 2.2.14-5, and yes, I
>know I should update it anyways and that a SMP kernel will run on a UP
>system)
Yes, there are several ways. How do you want to know how to do
it, in C, or a bash script? sysconf is one way, parsing
/proc/cpuinfo and /proc/stat is another. Beware though, if you
parse /proc/cpuinfo or stat, it is very different on different
architectures, particularly sparc.
Here is some code which should do it more or less correctly on
any arch:
ncpus=$(egrep -c ^cpu[0-9]+ /proc/stat || :)
[ "$ncpus" = "0" ] && ncpus=1
--
Mike A. Harris - Linux advocate - Free Software advocate
This message is copyright 2001, all rights reserved.
Views expressed are my own, not necessarily shared by my employer.
--
if (argc > 1 && strcmp(argv[1], "-advice") == 0) {
printf("Don't Panic!\n");
exit(42);
}
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Re: Detecting SMP
On Wed, 21 Feb 2001, Tigran Aivazian wrote: > So, one would normally expect this to mean an SMP board rather than > multiple processors, _HOWEVER_, I can imagine a very clever MP-aware BIOS > implementation which detects that there are many processors and prepares > MP floating config table and does _not_ prepare it otherwise. So, it all > depends on the BIOS implementation. I've seen systems that do so and while it's not forbidden I consider it a bad thing. It prevents us from being able to use I/O APICs. -- + Maciej W. Rozycki, Technical University of Gdansk, Poland + +--+ +e-mail: [EMAIL PROTECTED], PGP key available+ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Detecting SMP
yes, just run the famous mptable program. If the machine is SMP then it will have a valid Intel MP 1.4 configuration tables so the program will show meaningful output. Regards, Tigran On Tue, 20 Feb 2001, Burton Windle wrote: > Hello. Is there a way, when running a non-SMP kernel, to detect or > otherwise tell (software only; the machine is 2400 miles away) if the > system has SMP capibilties? Would /proc/cpuinfo show two CPUs if the > kernel is non-SMP? Thanks! > > (btw, the kernel in question is a stock RH6.2 kernel 2.2.14-5, and yes, I > know I should update it anyways and that a SMP kernel will run on a UP > system) > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Detecting SMP
What is the platform ( x86, Sparc, alpha or ?)? On sparc look in the bootprom (ls /proc/openprom) that works regardless of kernel SMP status. On Intel I think your out of luck, at least with the commonly available hardware/software. In theory there could be a bios-peeking structure in /proc much like openprom that could give you hints... Sent by: [EMAIL PROTECTED] To: [EMAIL PROTECTED] cc: Subject: Detecting SMP Hello. Is there a way, when running a non-SMP kernel, to detect or otherwise tell (software only; the machine is 2400 miles away) if the system has SMP capibilties? Would /proc/cpuinfo show two CPUs if the kernel is non-SMP? Thanks! (btw, the kernel in question is a stock RH6.2 kernel 2.2.14-5, and yes, I know I should update it anyways and that a SMP kernel will run on a UP system) -- Burton Windle [EMAIL PROTECTED] Linux: the "grim reaper of innocent orphaned children." from /usr/src/linux-2.4.0/init/main.c:655 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Detecting SMP
On Wed, 21 Feb 2001, Jeff Garzik wrote: > On Wed, 21 Feb 2001, Tigran Aivazian wrote: > > yes, just run the famous mptable program. If the machine is SMP then it > > will have a valid Intel MP 1.4 configuration tables so the program will > > show meaningful output. > > Does that allow you to detect multiple processors... or just an SMP board? > the answer is in section 4.1 of the Intel MP 1.4 spec: "An MP-compliant system must implement the MP floating pointer structure, ..." So, one would normally expect this to mean an SMP board rather than multiple processors, _HOWEVER_, I can imagine a very clever MP-aware BIOS implementation which detects that there are many processors and prepares MP floating config table and does _not_ prepare it otherwise. So, it all depends on the BIOS implementation. Actually, I never tried unplugging all-1 processors from my SMP machines and seeing what sort of MP table is left... Regards, Tigran - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Detecting SMP
On Wed, 21 Feb 2001, Tigran Aivazian wrote: > yes, just run the famous mptable program. before I am snowed under with questions about where to get this program, here is the src and binaries that I use -- it is quite possible that there is a newer version (I suspect Ingo Molnar might know better :) http://www.moses.uklinux.net/mptable Regards, Tigran - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: Detecting SMP
On Wed, 21 Feb 2001, Tigran Aivazian wrote: > yes, just run the famous mptable program. If the machine is SMP then it > will have a valid Intel MP 1.4 configuration tables so the program will > show meaningful output. Does that allow you to detect multiple processors... or just an SMP board? Jeff - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Detecting SMP
Hello. Is there a way, when running a non-SMP kernel, to detect or otherwise tell (software only; the machine is 2400 miles away) if the system has SMP capibilties? Would /proc/cpuinfo show two CPUs if the kernel is non-SMP? Thanks! (btw, the kernel in question is a stock RH6.2 kernel 2.2.14-5, and yes, I know I should update it anyways and that a SMP kernel will run on a UP system) -- Burton Windle [EMAIL PROTECTED] Linux: the "grim reaper of innocent orphaned children." from /usr/src/linux-2.4.0/init/main.c:655 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
