Re: ARM - EPICS performance evaluation

[Peter Jemian <jemian@anl.gov>]

Follow that google.com link and you will see the context of the 4 ms interval.  The article shows how it can go faster.

Pete



----- Reply message -----
From: "John William Sinclair" <sinclairjw@ornl.gov>
Date: Sat, Mar 17, 2012 9:25 am
Subject: ARM - EPICS performance evaluation
To: "Emmanuel Mayssat" <emayssat@yahoo.com>
Cc: "epics" <tech-talk@aps.anl.gov>

4ms for one AI reading seem completely unreasonable. Are you sure?

Emmanuel Mayssat wrote:
>
> Well, I am not sure what you call performance evaluation.
> But as far as running epics/seq/etc, that's no problem.
> (I used 3.14.11 with minimal patching)
>
> The issue you may be facing is I/O access.
> On the ts7370 (ARM9), it takes me 4ms to get a AI reading.
> The main issues on this board is
> 1/ no buffering
> 2/ you are running a full blown linux OS
>
> For higher througput, I am looking at microcontrollers (arduino megas 
> or more advanced)
> Read this to get a flavor of the issues ;)
> http://sites.google.com/site/measuringstuff/the-arduino
>
> To have a full blown arm production deployment (as we are strongly 
> considering),
> there are practical issues:
> 1/ management of SD images (SD card)
> 2/ controlled upgrade/change of SD image
>
> To bypass those issues, we are going in the direction of
> beagleboard-xm (full blown linux desktop environment, with epics IOC 
> but no direct critical I/O)
> attached to microcontrollers (for critical I/O)
> Cost of parts ~ $200
>
> One of my coworkers called this design 'smart chassis': with the spare 
> IO, you can monitor the environment (temp, vibration, etc)
> I call it 'epics plug-and-play': You plug your chassis to your network 
> and the epics PV are immediately available.
> For maintenance, when the hardware is swapped/changed, the ioc 
> software is changed with it.
> For troubleshooting on the bench, engineers/technicians can attach a 
> keyboard and a monitor to a chassis and immediately start working. (Qt 
> works great with embedded systems ;)
> We design a lot of our electronics, so by using open hardware 
> solutions, we can *in theory* integrate the ARM+ucontroller directly 
> in our electronics design (maybe at 2nd generation design)
> ...etc...
>
> In short, they are several advantages to this design which fit *OUR* 
> needs.
>
> Looking forward ARM cpu are becoming more and more powerful, epics/qt 
> is on the way...
> You see, the tide is also going that direction...
>
>
>
> ------------------------------------------------------------------------
> *From:* "ssahoo@vecc.gov.in" <ssahoo@vecc.gov.in>
> *To:* Emmanuel Mayssat <emayssat@yahoo.com>
> *Sent:* Friday, March 16, 2012 9:39 AM
> *Subject:* Re: EPICS performance evaluation
>
> Yes, I am using TS7500 from embeddedarm (ARM9).. 
>
> So, have u performed any performance evaluation test for ur arm platform.
>
> Thanking you,
>
>