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

Subject: Re: ARM - EPICS performance evaluation
From: John William Sinclair <sinclairjw@ornl.gov>
To: Emmanuel Mayssat <emayssat@yahoo.com>
Cc: epics <tech-talk@aps.anl.gov>
Date: Sat, 17 Mar 2012 10:22:07 -0400
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,




References:
EPICS performance evaluation ssahoo
Re: ARM - EPICS performance evaluation Emmanuel Mayssat

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