Zander Z365 wrote: >Thanks to all of you for helping me. I can successfully emerge X & >KDE using an SMP kernel and hard setting the CPU frequency. However, >using an SMP kernel 'cat /proc/cpuinfo' nor 'x86info -mhz' seem to >show the new cpu frequency. I do have two more questions: > >
Strange...my P4 3Ghz HT reports this fine in /proc/cpuinfo. What does your dmesg output say about your processor(s)? You should have something similar to: Apr 11 08:20:55 carcharias CPU0: Intel(R) Pentium(R) 4 CPU 3.00GHz stepping 09 Apr 11 08:20:55 carcharias CPU1: Intel(R) Pentium(R) 4 CPU 3.00GHz stepping 09 Are you sure you selected the right processor family? Also, did you enable the SMT (hyperthreading) scheduler in the kernel? >1. Using a Uni-processor kernel it appears I do not have to decrease >my cpu frequency to emerge large products or compiles. Will I loose a >great deal of performance using it since I really only have one cpu >(even though It has HT technology)? > > Well, 99% of the time, it won't make any difference. But, yes, I can notice it on my laptop. I would say the hit is about 20%. Of course, my CPU only has 512K of L2 cache, compared to your, what was it, 2M?, so it might not make as big a difference for you. The reason is because HT really only helps when you have cache-misses, and data must be fetched from RAM. This takes several clock cycles to complete, during which time nothing else can run in the execution unit of the processor. HT adds another instruction pipeline, so as long as at least one of the two pipelines can make progress, the execution unit is in use. So fewer cache misses for you should mean less of an impact. >2. Will 'speedfreq' work with SMP kernels? > > Yes. -Richard -- gentoo-user@gentoo.org mailing list
