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<== Date ==> <== Thread ==>

Subject: RE: Does EPICS Base support multi-thread on vxWorks 6.3?
From: [email protected]
To: "Jeff Hill" <[email protected]>
Cc: [email protected]
Date: Tue, 19 Apr 2011 17:26:42 +0800

The delay passed to ca_pend_event is 0.5s.

I changed to call ca_context_create with ca_enable_preemptive_callback (without any other change... and still calling ca_pend_event afterwards), and found out the CPU 100% usage issue was gone. Weird!

Lorna Zhang
National Instruments Shanghai
Tel: 86-21-50509810-3230



From: "Jeff Hill" <[email protected]>
To: <[email protected]>, "'Andrew Johnson'" <[email protected]>
Cc: <[email protected]>
Date: 04/19/2011 06:37 AM
Subject: RE: Does EPICS Base support multi-thread on vxWorks 6.3?





Ø  Is there any other reason that could cause similar issues?

 

What delay is being passed to ca_pend_event?

 

Otherwise, set a breakpoint in the function that uses CPU, to see who calls it, and how often.

 

Jeff

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Message content: TSPA

 

With sufficient thrust, pigs fly just fine. However, this is

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as they fly overhead. -- RFC 1925

 

From: [email protected] [mailto:[email protected]] On Behalf Of [email protected]
Sent:
Monday, April 18, 2011 2:59 AM
To:
Andrew Johnson
Cc:
[email protected]
Subject:
Re: Does EPICS Base support multi-thread on vxWorks 6.3?

 


I'm not sharing a single CA client context between threads, I did make a call to ca_context_create() with ca_disable_preemptive_callback when a new thread is initiated.


Is there any other reason that could cause similar issues?


Andrew, thanks for your recommendation of using ca_enable_preemptive_callback, but that might not be my first choice.


Lorna


From: Andrew Johnson <[email protected]>
To: [email protected]
Cc: [email protected]
Date: 04/15/2011 11:07 PM
Subject: Re: Does EPICS Base support multi-thread on vxWorks 6.3?

 





Hi Lorna,

On Friday 15 April 2011 02:34:53 [email protected] wrote:
>
> We developed a client based on libca (EPICS Base 3.14.9), which will
> create it's own worker thread on construction. But we found it working
> strangely on vxWorks (ppc-603). Whenever a second EPICS client is created
> (meaning there are now 2 EPICS worker threads on vxWorks), the CPU usage
> became 100%.
>
> From the profile, we found the ca_pend_event is consuming lots of the CPU.
>
> Meanwhile, it seems epicsMutex is failing to do the lock for the second
> EPICS client??

EPICS should work fine on your hardware and OS combination, this is probably
an application programming issue.

Are these two threads sharing a single CA client context?  Hopefully Jeff Hill
will respond here too, but you might want to read this and the following
sections of the CA Reference Manual for some ideas:
http://www.aps.anl.gov/epics/base/R3-14/12-docs/CAref.html#Thread
In particular if you're experienced in writing multi-threaded code you might
want to use ca_enable_preemptive_callback mode and completely avoid having to
call ca_pend_event() in your code.

- Andrew
--
An error is only a mistake if you don't learn from it.
When you learn something from it, it becomes a lesson.


Replies:
RE: Does EPICS Base support multi-thread on vxWorks 6.3? Jeff Hill
References:
Does EPICS Base support multi-thread on vxWorks 6.3? lorna . zhang
Re: Does EPICS Base support multi-thread on vxWorks 6.3? Andrew Johnson
Re: Does EPICS Base support multi-thread on vxWorks 6.3? lorna . zhang
RE: Does EPICS Base support multi-thread on vxWorks 6.3? Jeff Hill

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