A question about Intel HyperThreading
Chris at lainos.org
Sun Sep 18 12:37:42 PDT 2005
I don't think that would be the fault of hyperthreading.
Perhaps it's blocking or waiting in a loop until something happens?
That would explain why it's at ~50% regardless of if it's put under load or
I'm not sure what your software is doing, but my first guess is that there is
a loop in there somewhere which blocks until it gets something to do, but
doesn't sleep on the iterations where it doesn't have to do anything.
On Sunday 18 September 2005 21:14, Roger O. Svenning wrote:
> Due to a fatal hardware failure we replaced one of our AMD based
> NeverWinter Nights game -servers with an Intel Pentium 4 one running
> 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.
> Roger O. Svenning
> Bodø - Norway
> Top exctract:
> CPU states: 36.8% user, 0.0% nice, 13.2% system, 0.0% interrupt, 50.0%
> Mem: 189M Active, 520M Inact, 190M Wired, 24K Cache, 112M Buf, 1103M
> Swap: 4069M Total, 4069M Free
> PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU
> 4015 root 1 113 0 221M 123M RUN 0 0:37 51.22%
> 4019 root 1 113 0 221M 123M RUN 0 0:22 49.84%
> 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
> 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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