Some months ago I updated the kernel on several of my RHEL 4 systems from 2.6.9-5 to 2.6.9-84, and now it seems that the OS isn't detecting the 4 cores the server has. The only evidence I have that something is amiss is that one of those boxes that I did upgrade has yet to be rebooted, still is using the old kernel and still shows 4 processors. Other identical boxes with the new kernel are showing 1.

These servers are PE2850's with 2 dual-core Xeon processors. Dell's OpenManage product confirms that both sockets are filled, but Linux only shows 1 processor.

Is there a configuration directive somewhere for the kernel that dictates how many processors are recognized? Top, mpstat, and nmon each only show 1 proc per the affected servers, and /proc/cpuinfo only shows 1. Is it possible the OS is using all 4 cores but only displaying 1?

Thanks in advance!

DD

I think I just found out the issue. The systems upgraded weren't with SMP kernels.