how to programatically determine if hyperthreading is enabled in linux kernel

shawshank_blr · 07-01-2009, 04:49 AM

hi.. i know that the flag ‘ht’ in the /proc/cpuinfo flags section tells you that the physical cpu is capable of providing hyperthreading.

But how can i find out if the kernel is enabled for hyperthreading. Is there a way by which I can programatically find out this?
Please help….

unSpawn · 07-03-2009, 06:33 AM

I think the kernel just counts the amount of cores and switches from UP to MP?

syg00 · 07-03-2009, 07:14 AM

The kernel isn't ever "enabled" for hyperthreading. As unSpawn said, unless a kernel is specifically non-SMP, it will use all apparent CPUs for dispatch. Hyperthreading is of course not really multiple CPUs (cores), hence the use of "apparent".
There is an indicator to assist the scheduler (CONFIG_SCHED_SMT ), but I don't know of a way to test for it other than the obvious scan of the kernel config file, which may not be available in all cases.