[lkml]   [2002]   [Apr]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectHyperthreading and physical/logical CPU identification
Hello all,

I would like to know if there is any way to confirm that I have
hyperthreading enabled, and my P4 CPUs are hyperthreaded. Actually, from
something like /proc/cpuinfo, I'd like to figure out if I am seeing 2/4
physical/logical processors, as a result from hyperthreading, or 4/4
physical/logical processors with no hyperthreading. I know, "If it's double
the number of physical processors, well you have hyperthreading enabled."
The problem is, I have 4 physical processors, but kernels so far
do not recognize all of them. 2.4.18 will find 3, while 2.5.11 will find
only 2 (BIOS hyperthreading support off, no acpismp=force). However, on
2.5.11, if I enable hyperthreading (thru BIOS and acpismp=force, I see 4

I would very much like to believe that in this configuration, I am only
running on 2 physical, 4 logical processors, but I am getting a 31%
improvement (netbench) when hyperthreading is enabled. Thats why I want to
confirm I am really only using 2 physical, 4 logical processors. Is there
any way I can do this? (dmesg? /proc/cpuinfo?)


Andrew Theurer
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:25    [W:0.047 / U:16.132 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site