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isolcpus question

DISCUSSION Gene Heskett 2 participants 3 messages Jan 31, 2012

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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

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Quoted 6 lines · 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.

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

#2 lore raw
Quoted 9 lines · Mike Galbraith
Quoted 7 lines · 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.

Quoted 5 lines

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:
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#!/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

Signature · 7 lines
"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.
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