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Subject: Re: "spinlock" API
From: Michael Davidsaver <mdavidsaver@bnl.gov>
To: Andrew Johnson <anj@aps.anl.gov>
Cc: core-talk@aps.anl.gov
Date: Fri, 08 Jun 2012 17:53:05 -0400
On 6/8/2012 3:48 PM, Andrew Johnson wrote:
Hi Michael,

On 2012-06-07 Michael Davidsaver wrote:
For the implementation of thread pool I would like to allow it to be
used from interrupt context on RTEMS/vxworks.  So it should need to use
epicsInterruptLock().  I want to avoid using a global lock on
Linux/Windows/etc.

Now I could implement this internally for the thread pool only, but I
thought I would float the possibility of creating a proper spin lock
API.  Initially RTEMS/vxworks would implement this using epicsInterrupt
and the default implement would use epicsMutex.
Have you looked at the epicsAtomicLock() and epicsAtomicUnlock() routines that
Jeff uses in some of his epicsAtomic implementations?

It looks like the current posix implementation uses a global lock similar to epicsInterrupt. Do you see a way this could be avoided?

http://bazaar.launchpad.net/~epics-core/epics-base/3.15/view/head:/src/libCom/osi/os/posix/epicsAtomicOSD.cpp#L48


... but they do seem to be implementing the functionality
you're after;

My goal for the thread pool implementation is to, as much as possible, allow two pools to function independently. Having a global mutex used in the queuing and dequeuing processes seems a likely point of contention.

This lock is not held when queued jobs are executed, but is taken by each worker thread after each job is executed. So it does see quite a bit of use.


Michael


Replies:
Re: "spinlock" API Andrew Johnson
References:
"spinlock" API Michael Davidsaver
Re: "spinlock" API Andrew Johnson

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