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Subject: Re: Increasing scan rate to 10 kHz
From: Evgeniy <tikh@triumf.ca>
To: Eric Norum <eric@norum.ca>
Cc: EPICS Tech Talk <tech-talk@aps.anl.gov>
Date: Wed, 18 Dec 2013 11:07:24 -0800
Processing of an EPICS record takes ~2 milliseconds on my SL5.3/DELL 2.27 GHz. It is unbelievably slow!
Is it possible to shorten this time without rebuilding Linux kernel?


-------- Original Message --------
On Nov 27, 2013, at 11:29 AM, Evgeniy <tikh@triumf.ca> wrote:

Thanks, Andrew and Emmanuel for your replies.

I am running Soft IOC on Dell server (64 bit) with eight  Intel Xeon CPUs, each  2.27GHz.
It seems that syntax for dbd file is correct. I found that minimum scan period for my system is 0.001 seconds. For shorter periods it falls down to 0.1 second, as Andrew mentioned.
The difference in one CPU usage is only 5% if I run records with scan 0.1 second or 0.001 second. It looks like it is limitation of EPICS, not hardware.
Or perhaps the kernel timer implementation has a resolution of 1 ms?
  What is the bottleneck for processing of a record on GHz CPUs?
Is it possible to improve it?

Evgeniy


Replies:
RE: Increasing scan rate to 10 kHz Mark Rivers
Re: Increasing scan rate to 10 kHz Andrew Johnson
References:
Increasing scan rate to 10 kHz Evgeniy
Re: Increasing scan rate to 10 kHz Andrew Johnson
Re: Increasing scan rate to 10 kHz Evgeniy
Re: Increasing scan rate to 10 kHz Eric Norum

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