How to check hyperthreading on HP-UX ?

[lingzong]

Hello..

I am using an HP-UX 11i v3 System. How can I (what command) check if hyperthreading is really working in this system?

This system has 4 processors.

bash-3.2# ioscan -fCprocessor
Class I H/W Path Driver S/W State H/W Type Description
========================================================================
processor 0 120 processor CLAIMED PROCESSOR Processor
processor 1 121 processor CLAIMED PROCESSOR Processor
processor 2 122 processor CLAIMED PROCESSOR Processor
processor 3 123 processor CLAIMED PROCESSOR Processor


The hyperthreading was enabled with setboot:

bash-3.2# setboot
Primary bootpath : 0/1/1/0.0x5000c5000c9a6af5.0x0 (/dev/rdisk/disk2)
HA Alternate bootpath : 0/1/2/0 (LAN Interface)
Alternate bootpath : 0/1/2/1 (LAN Interface)

Autoboot is ON (enabled)
Hyperthreading : ON
: ON (next boot)

I'd expect to see 8 processors virtually.

However, in my applications, I can only see 4 processors.

HP-UX pisa B.11.31 U ia64 02/26/09

23:09:53 cpu %usr %sys %wio %idle
23:09:58 0 81 13 0 6
2 81 14 0 5
4 80 13 0 7
6 75 18 0 7
system 79 14 0 6
23:10:03 0 24 8 9 59
2 27 9 22 42
4 28 9 7 56
6 22 9 7 62
system 25 9 11 54

Any idea to check where are those CPUs --1, 3, 5, 7? Thanks

[sujit kumar singh]

hi


You can also see by checking the follwing things as such , are you having VPARs on the system?

Try posting the
#parstatus
#vparstatus
#model

Etc from the Machine.

regards
sujit

[Robert-Jan Goossens]

Hi,

Actually hyper-threading is set on the OS level (11iV3).

# kctune | grep lcpu_attr

lcpu_attr

This tunable dynamically enables (1) or disables (0) the logical processor (LCPU) attribute in the default processor set. On systems supporting hyper-threading technology, each hyper-thread is represented as an LCPU.

http://docs.hp.com/en/B2355-60130/lcpu_attr.5.html

Have a look at the output from the machinfo command.

Cores > cpus > threads
1 2 4

Regards,
Robert-Jan

[smatador]

Hi,

For hp-ux 11iv3, you can enable hyperthreading by two way
HP-UX#setboot -m on
or EFI#cpuconfig threads on
but enabling or disabling HT is not supported on vPars you can enable/disable HT from vpmon

MON> threads on
HyperThreading is now set to be ON after the next reboot

to be complete see the doc of setboot
http://docs.hp.com/en/setbootv3/setboot.pdf

Hope it helps

[lingzong]

Hello All,

Thanks so much for the information.

The problem is discovered by using the command of "kctune | grep lcpu_attr".
___________________________________________

# kctune | grep lcpu_attr
lcpu_attr 0 0 Imm (auto disabled)
___________________________________________

Then I enabled it:
___________________________________________
# kctune -B lcpu_attr=1
* The automatic 'backup' configuration has been updated.
* Future operations will update the backup without prompting.
* The requested changes have been applied to the currently
running configuration.
Tunable Value Expression Changes
lcpu_attr (before) 0 0 Imm (auto disabled)
(now) 1 1
# kctune | grep lcpu_attr
lcpu_attr 1 1 Imm (auto disabled)
____________________________________________

Now, my appliaction can run with 8 procs.
____________________________________________
HP-UX pisa B.11.31 U ia64 02/28/09

14:04:09 cpu %usr %sys %wio %idle
14:04:14 0 0 0 0 100
1 0 0 0 100
2 0 0 0 99
3 0 0 0 99
4 2 1 0 96
5 3 1 0 96
6 0 0 0 100
7 0 0 0 100
system 1 0 0 99
____________________________________________

Thanks again!

[Dennis Handly]

>Now, my application can run with 8 procs.

This may be an illusion. Whether hyperthreading benefits your application depends on what it's doing.

[lingzong]

Yes. The benefits of hyperthreading is another issue.
In fact, it isn't clear that hyperthreading will actually improve the performance of my applications - I've never seen much effect on Windows either.
Here, I just want to make sure the hyperthreading is visually working on this HP system, and then move forward.

Thanks for your attention.