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Getting Linux to recognize a second core

J

jcromano

Member
Hi,

Last night I upgraded from my single core 3000+ to a dual core 4800+ X2. My system is dual boot--Windows XP Home and Linux Fedora Core 6.

Windows recognized the new core right away, and it seems to be humming along there.

Linux still runs, but I'm not sure it's recognizing the second core and taking advantage of it.

So, I have some questions for the Linux experts out there...
a) How can I tell for sure if Linux has found and is using the second core?
b) What needs to be done to get Linux to use both cores? I suspect the answer will involve the letters "smp," but that's just a guess.

I am pretty much a Linux novice, so simple answers would definitely be preferred. Any solution that can be done entirely through yum would be great.

Jim
 
top has an option to look at other cores...

from the terminal, run "top" and hit 1 to show CPU's separately.

If you don't have them, you may need to install the SMP kernel. Not sure how Fedora names their packages. Use YUM to find the most recent kernel that is also labeled SMP
 
If it's an AMD64 kernel it probably has SMP enabled by default, if it's a 32-bit kernel then you'll need to find and install an SMP kernel.
 
Thanks for your answers, nweaver and Nothinman. "top" shows two cpus that are being used. The kernel was an x86_64.

So I guess I'm good.

Cheers.
 
Working as intended then.
If you wanna view info about your CPU(s), you can always go to your nearest command line and type "cat /proc/cpuinfo".
That'll show various info about all CPU's in your system, type, speeds, capabilities, etc.
 
I think that /proc/cpu will sometimes show the multiple cores/procs, even if the kernel is not using them (iirc)
 
I think that /proc/cpu will sometimes show the multiple cores/procs, even if the kernel is not using them (iirc)
Click to expand...

No, it shows all of the active CPUs. Even taking a CPU offline at runtime updates /proc/cpuinfo.
 
Newer kernels do not have smp and non-smp versions, even for x86. It's been combined into one kernel and it detects whether or not to load the smp code at boot time. I know Fedora Core 6 and probably Core 5 have new enough kernels for this, and so does Ubuntu Dapper or later.

That is why you did not have to do anything.
 
Originally posted by: Nothinman
If it's an AMD64 kernel it probably has SMP enabled by default, if it's a 32-bit kernel then you'll need to find and install an SMP kernel.
Click to expand...
Why would SMP be a default for amd64? The majority of them are not dual core.
 
Why would SMP be a default for amd64? The majority of them are not dual core.
Click to expand...

Because it doesn't hurt performance and less configs are easier to maintain, especially now with the "SMP alternatives" stuff it detects if there's only one CPU and "downgrades" to UP mode.
 
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