Hyperthreading hurts 5.3?
atkielski.anthony at wanadoo.fr
Wed Jan 12 09:41:06 PST 2005
Giorgos Keramidas writes:
GK> You need to enable SMP too, to allow the FreeBSD kernel to use the
GK> second (hyper-threaded) CPU.
I found it, in a file called SMP. Why is the SMP option tucked away in
a separate file?
I stuck this into the config and rebuilt the kernel. Seems to run fine.
I see that top has a C column now, and running a program in a continuous
loop takes up exactly 50% of the machine (and two such programs take up
exactly 100%), according to top.
Boot messages looked a bit different:
The Regents of the University of California. All rights reserved.
FreeBSD 5.3-RELEASE #0: Wed Jan 12 17:55:18 CET 2005
root at freebie.atkielski.com:/usr/obj/usr/src/sys/FREEBIE-SMP
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (2998.57-MHz 686-class CPU)
Origin = "GenuineIntel" Id = 0xf34 Stepping = 4
Hyperthreading: 2 logical CPUs
real memory = 1073414144 (1023 MB)
avail memory = 1045061632 (996 MB)
ACPI APIC Table: <A M I OEMAPIC >
FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
cpu0 (BSP): APIC ID: 0
cpu1 (AP): APIC ID: 1
cpu0: <ACPI CPU> on acpi0
cpu1: <ACPI CPU> on acpi0
SMP: AP CPU #1 Launched!
So I guess it's all working now. That was easy.
I imagine this will give me a bit more horsepower for the buck,
although--with only 0.2% of the machine busy under normal load even with
a single processor--I guess I wasn't exactly processor-bound to begin
with (I'd run out of I/O capacity long before running out of processor).
But why not profit from what's there, eh?
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