A question about Intel HyperThreading

Roger O. Svenning roger at audioweb.no
Sun Sep 18 12:15:17 PDT 2005


Hi

Due to a fatal hardware failure we replaced one of our AMD based
NeverWinter Nights game -servers with an Intel Pentium 4 one running
6.0-beta4

This is the first Pentium based box we've set up and I was hoping
someone can explain the weird cpu usage behaviour we see.

Look at the top extract below and notice the 50% idle value.
No matter what, it sits at 50% idle all the time when the nwserver
process is running.

Neither have I ever seen top reporting any process using the other
logical cpu, so basically it sits at 50% idle no matter how much load I
throw at it.

The nwserver service is not multithreaded and I'm guessing it's using
only one of the logical cpus, but are there actually processing power
sitting idle here or is it just a top-weirdness?

Needless to say I want the nwserver process to be able to use all
processing power available in the cpu.


Regards

Roger O. Svenning
-----------------
Bodø - Norway

-------------
Top exctract:
-------------
CPU states: 36.8% user,  0.0% nice, 13.2% system,  0.0% interrupt, 50.0%
idle
Mem: 189M Active, 520M Inact, 190M Wired, 24K Cache, 112M Buf, 1103M
Free
Swap: 4069M Total, 4069M Free

  PID USERNAME  THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU
COMMAND
 4015 root        1 113    0   221M   123M RUN    0   0:37 51.22%
nwserver
 4019 root        1 113    0   221M   123M RUN    0   0:22 49.84%
nwserver

---------------
Dmesg exstract:
---------------
FreeBSD 6.0-BETA4 #0: Fri Sep 16 01:17:42 UTC 2005
    root at nwn.patnix.nl:/usr/obj/usr/src/sys/NEWKERNSMP
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (2994.91-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf41  Stepping = 1
 
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,SSE2,SS,HTT,TM,PBE>
  Features2=0x441d<SSE3,RSVD2,MON,DS_CPL,CNTX-ID,<b14>>
  Hyperthreading: 2 logical CPUs
real memory  = 2146304000 (2046 MB)
avail memory = 2095374336 (1998 MB)
ACPI APIC Table: <IntelR AWRDACPI>
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
 cpu0 (BSP): APIC ID:  0
 cpu1 (AP): APIC ID:  1
ioapic0: Changing APIC ID to 2
ioapic0 <Version 2.0> irqs 0-23 on motherboard
ioapic1 <Version 2.0> irqs 24-47 on motherboard



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