to hyperthread or not to hyperthread
h at schmalzbauer.de
Sat Dec 20 03:40:26 PST 2003
On Friday 19 December 2003 23:34, Scott Long wrote:
> On Fri, 19 Dec 2003, Mike Tancsa wrote:
> > We are replacing a box that is fairly busy with many different processes
> > (sendmail / pop3). The new MB and CPU is hyperthreading capable. Is it
> > worth it to enable this ? Does anyone have any real world experiences
> > with it in RELENG_4 that say one way or the other to use or not use it ?
> > dmesg shows,
> > CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (2992.52-MHz 686-class CPU)
> > Origin = "GenuineIntel" Id = 0xf29 Stepping = 9
> > Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,
> >MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,S SE2,SS,HTT,TM,PBE>
> > Hyperthreading: 2 logical CPUs
> > ---Mike
> HyperThreading usually requires special smarts in the OS process
> scheduler so that the cores don't bottleneck each other with cache
> thrashing and pipeline stalls/starvation. Without this, Hyperthreading
> is usually slightly slower than non-Hyperthreading. 4.x does not have
> a scheduler that understand HTT, but 5.2-CURRENT does.
Do you mean ULE or 4BSD regarding HTT capable?
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