Hyperthreating

[niki]

Hi all,

Im starting in Linux. I have a Dell8300 comp with hyperthreating. Bios is set to hyperthreating. In Windows I can easily check out wether HT is on or not. Is there a way to check this in Kubuntu? Can't find it anywhere. Perhaps via Console, but this is new to me so I greatly appreciate some tips on that.

thanks
Niki

[zaflaucich]

Re: Hyperthreating

I had the same "problem"
you need to install "linux-686-smp" and all his depencies.
smp stands for symmetric multi-processing
Then reboot selecting the smp kernel

In a terminal, you can easly check it with "uname -v": if it's enabled you get "SMP" in the answer

[niki]

Re: Hyperthreating

thx for the quick reply zaflaucich.

I downloaded linux-686-smp with aptitude, performed a reboot.
Now I see the smp-kernel in my grub menu. So far so good.
When I pick either the recovery mode or the grap mode my comp simply reboots.
So HT doesn't seem to work on my comp.
What could be the problem here?
Do you need extra info to be able to give an answer?

thx
niki

[zaflaucich]

Re: Hyperthreating

You could select the non-SMP kernel at boot and go to see in /var/log/ directory if there is some information on the cause of the reboot..... That's what I would do in this case

[niki]

Re: Hyperthreating

thx, will do

[niki]

Re: Hyperthreating

hmmmm,

looked in the /var/log dir, found lots of files. Don't know which one to look for.
Removed and reinstalled the smp - kernel, was able to boot the smp in graph mode once. Had HT on (checked with cat /proc/cpuinfo).
Did a reboot after and was back with the same problem : system reboots.

Can you tell me which file exactly to look for?

thx
niki

[robins_web]

Re: Hyperthreating

There is a difference between hyperthreading--which is what single-processor machines do--and SMP (Simultaneous Multi Processing), which is what machines with more than one processor (i.e., CPUs) do.

Unless your machine has more than one CPU, the SMP kernel won't work.

[niki]

Re: Hyperthreating

Well, actually the smp-kernel did work the first time i logged on and i was able to see 2 cpu's (as if the ht is on).
If the SMP isn't the correct kernel for ht (which i suppose is true since i cant boot it anymore) can anybody tell me how to enable my hyperthreading pls?

thx
niki

[zaflaucich]

Re: Hyperthreating

I have a single pentium 4 3.2 GHz, single core with hypertrading.
I have installed SMP image kernel and it works well (my computer is on 24/7)

Searching in the ubuntu forum, I have found this:
http://www.ubuntuforums.org/showpost...85&postcount=1

Anyway tomorrow I'll check if the 686 (non smp) kernel has the HT enabled

[zaflaucich]

Re: Hyperthreating

I'm sorry but I can't give a try to non smp image kernel (this is my pc at work, and for now I can't shut it down)

I can give you these informations (hope they help)

uname -v
#1 SMP PREEMPT Fri Sep 8 20:16:40 UTC 2006

 dmesg |grep CPU
[17179569.184000] Initializing CPU#0
[17179569.560000] CPU: After generic identify, caps: bfebfbff 00000000 00000000 00000000 0000441d 00000000 00000000
[17179569.560000] CPU: After vendor identify, caps: bfebfbff 00000000 00000000 00000000 0000441d 00000000 00000000
[17179569.560000] CPU: Trace cache: 12K uops, L1 D cache: 16K
[17179569.560000] CPU: L2 cache: 1024K
[17179569.560000] CPU: Hyper-Threading is disabled
[17179569.560000] CPU: After all inits, caps: bfebfbff 00000000 00000000 00000080 0000441d 00000000 00000000
[17179570.040000] CPU0: Intel(R) Pentium(R) 4 CPU 3.20GHz stepping 04
[17179570.048000] Initializing CPU#1
[17179570.132000] CPU: After generic identify, caps: bfebfbff 00000000 00000000 00000000 0000441d 00000000 00000000
[17179570.132000] CPU: After vendor identify, caps: bfebfbff 00000000 00000000 00000000 0000441d 00000000 00000000
[17179570.132000] CPU: Trace cache: 12K uops, L1 D cache: 16K
[17179570.132000] CPU: L2 cache: 1024K
[17179570.132000] CPU: Hyper-Threading is disabled
[17179570.132000] CPU: After all inits, caps: bfebfbff 00000000 00000000 00000080 0000441d 00000000 00000000
[17179570.132000] CPU1: Intel(R) Pentium(R) 4 CPU 3.20GHz stepping 04
[17179570.276000] checking TSC synchronization across 2 CPUs: passed.
[17179570.280000] Brought up 2 CPUs
[17179582.028000] ACPI: Processor [CPU1] (supports 8 throttling states)
[17179582.028000] ACPI: Processor [CPU2] (supports 8 throttling states)

cat /proc/cpuinfo 
processor    : 0
vendor_id    : GenuineIntel
cpu family   : 15
model      : 3
model name   : Intel(R) Pentium(R) 4 CPU 3.20GHz
stepping    : 4
cpu MHz     : 3200.682
cache size   : 1024 KB
fdiv_bug    : no
hlt_bug     : no
f00f_bug    : no
coma_bug    : no
fpu       : yes
fpu_exception  : yes
cpuid level   : 5
wp       : yes
flags      : 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 ht tm pbe p
ni monitor ds_cpl cid xtpr
bogomips    : 6408.23

processor    : 1
vendor_id    : GenuineIntel
cpu family   : 15
model      : 3
model name   : Intel(R) Pentium(R) 4 CPU 3.20GHz
stepping    : 4
cpu MHz     : 3200.682
cache size   : 1024 KB
fdiv_bug    : no
hlt_bug     : no
f00f_bug    : no
coma_bug    : no
fpu       : yes
fpu_exception  : yes
cpuid level   : 5
wp       : yes
flags      : 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 ht tm pbe p
ni monitor ds_cpl cid xtpr
bogomips    : 6400.60

It's 'funny' that dmesg says that I have 2 CPU without HT....
It would be nice to have this clarified

[niki]

Re: Hyperthreating

Hi,

thx again for the reply. I'll compare youre data with mine to see if something comes out of it.
Though i wont be able to reply in the coming days since im out of the country till the end to the month.
If you should find something interesting do let me know.
I'll keep looking... if i find something interesting ill also post it.

greetings
niki

[zaflaucich]

Re: Hyperthreating

i have asked to the 'debian guru' in my workplace, and he let me notice this:

http://www.daemonology.net/hyperthre...dered-harmful/

need more to investigate

[niki]

Re: Hyperthreating

this is what i get wen i perform the same commands:


niki@Dell8300:~$ uname -v
#1 PREEMPT Sat Sep 16 01:51:59 UTC 2006
niki@Dell8300:~$ dmesg |grep CPU
[17179569.184000] WARNING: NR_CPUS limit of 1 reached.  Processor ignored.
[17179569.184000] Initializing CPU#0
[17179572.812000] CPU: After generic identify, caps: bfebfbff 00000000 00000000 00000000 00004400 00000000 00000000
[17179572.812000] CPU: After vendor identify, caps: bfebfbff 00000000 00000000 00000000 00004400 00000000 00000000
[17179572.812000] CPU: Trace cache: 12K uops, L1 D cache: 8K
[17179572.812000] CPU: L2 cache: 512K
[17179572.812000] CPU: After all inits, caps: bfebfbff 00000000 00000000 00000080 00004400 00000000 00000000
[17179572.812000] CPU: Intel(R) Pentium(R) 4 CPU 2.80GHz stepping 09


No HT anywhere.....

thx
niki

[zaflaucich]

Re: Hyperthreating

My 'debian guru' confirmed me that to be able to use HT the SMP must be selected.
Anyway you could try to edit the file

/boot/grub/menu.lst

and add

ht=on

as option for the kernel boot command. Mine is this:

kernel     /boot/vmlinuz-2.6.15-26-686 root=/dev/hdb1 ro ht=on

[niki]

Re: Hyperthreating

Well, i actually tried with putting ht=on in my grub menu but the kernel simply wont boot. The moment i push enter my comp simply reboots.

This is what my grub menu looks like:

title           Ubuntu, kernel 2.6.15-27-686
root            (hd0,1)
kernel          /boot/vmlinuz-2.6.15-27-686 root=/dev/hda2 ro ht=on quiet splash
initrd          /boot/initrd.img-2.6.15-27-686
savedefault
boot

title           Ubuntu, kernel 2.6.15-27-686 (recovery mode)
root            (hd0,1)
kernel          /boot/vmlinuz-2.6.15-27-686 root=/dev/hda2 ro ht=on single
initrd          /boot/initrd.img-2.6.15-27-686
boot

title           Ubuntu, kernel 2.6.15-27-386
root            (hd0,1)
kernel          /boot/vmlinuz-2.6.15-27-386 root=/dev/hda2 ro quiet splash
initrd          /boot/initrd.img-2.6.15-27-386
savedefault
boot

title           Ubuntu, kernel 2.6.15-27-386 (recovery mode)
root            (hd0,1)
kernel          /boot/vmlinuz-2.6.15-27-386 root=/dev/hda2 ro single
initrd          /boot/initrd.img-2.6.15-27-386
boot


Can't find anything wrong here. Just can't figure out why the smp-kernel wont
boot. Since it actually did boot once (the very first time, since then it simply wont work...)
Going to the 386-kernel works fine every time...




niki