isolcpus question

isolcpus question

[Gene Heskett]

Which is, is there a isolcpus troubleshooting tool?

I have an app that is supposed to use the 2nd cpu on a 2 core atom system 
all by itself, and its insisting on using cpu0 when the boot command line 
has "isolcpus=1" appended to it, and apparently I am the only one with the 
problem, its working for about 200-500 others running the same software.

Cheers & thanks to anyone who can toss me a clue, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene>
There are three things men can do with women: love them, suffer for them,
or turn them into literature.
		-- Stephen Stills

Re: isolcpus question

[Mike Galbraith]

On Mon, 2012-01-30 at 22:13 -0500, Gene Heskett wrote:
> Which is, is there a isolcpus troubleshooting tool?
> 
> I have an app that is supposed to use the 2nd cpu on a 2 core atom system 
> all by itself, and its insisting on using cpu0 when the boot command line 
> has "isolcpus=1" appended to it, and apparently I am the only one with the 
> problem, its working for about 200-500 others running the same software.

isolcpus=1 isolates CPU1 so no task will automatically end up using it,
but it's up to your task (or you) to move to the isolated CPU.  Pin your
task to CPU1 with taskset, and all should work fine.

	-Mike

Re: isolcpus question

[Gene Heskett]

On Monday, January 30, 2012, Mike Galbraith wrote:
>On Mon, 2012-01-30 at 22:13 -0500, Gene Heskett wrote:
>> Which is, is there a isolcpus troubleshooting tool?
>> 
>> I have an app that is supposed to use the 2nd cpu on a 2 core atom
>> system all by itself, and its insisting on using cpu0 when the boot
>> command line has "isolcpus=1" appended to it, and apparently I am the
>> only one with the problem, its working for about 200-500 others
>> running the same software.
>
>isolcpus=1 isolates CPU1 so no task will automatically end up using it,
>but it's up to your task (or you) to move to the isolated CPU.  Pin your
>task to CPU1 with taskset, and all should work fine.
>
>	-Mike

Cross-posted back to the emc-users list, others might find it useful also.

Mike, you're a genius. The man page for taskset is a bit obtuse but the 
first stab at a '/usr/bin/lcnc' script:
-------------
#!/bin/bash
taskset 0x00000002 emc -l
exit 0
-------------
Seems to launch this application and I believe its now working better than 
ever before.  Now I need to do some experimenting to see just how fast I 
can make linuxcnc's base_thread run without the rest of the box getting 
laggy.  The faster I can make that thread run, the faster and smoother my 
steppers driving my milling machine will run.  I have already cut it down 
to 30 u-secs from 65 u-secs and it is still only using about 26% of the 
target cpu1.  Amazing IMO.

Thank you very much Mike.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene>
When a lion meets another with a louder roar,
the first lion thinks the last a bore.
		-- G.B. Shaw