Experimental Physics and
Industrial Control System

Mark Rivers <[email protected]> · Mon, 10 Sep 2012 22:21:03 +0000

Here is the output of "time" when running it in a mode where "top" showed the application using about 95% of a single CPU (on a 16 core system).  This is with my calculations enabled.

23.547u 16.516s 0:52.39 76.4%   0+0k 0+24io 0pf+0w

This is the output of time when the calculations are disabled and top shows about 80% CPU in my application.

Disabling my calculations:
11.401u 8.008s 0:27.60 70.2%    0+0k 0+8io 0pf+0w

So it spends a substantial amount of CPU time in both User Mode and Kernel Mode.

Mark

-----Original Message-----
From: J. Lewis Muir [mailto:[email protected]] 
Sent: Monday, September 10, 2012 5:03 PM
To: Mark Rivers
Cc: [email protected]
Subject: Re: How to profile an EPICS application on Linux

On 9/10/12 4:58 PM, Mark Rivers wrote:
> Hi Lewis,
> 
> Thanks for the reply. 
> 
> I don't think that could be it, because I can reduce the CPU time of my application from 20% to 14% by changing a PV to eliminate calculations that are definitely done in my code.  I collected the profile with those calculations enabled, so at least (20-14)/20 = 30% of the CPU time should be in my calculation function.  It's spending the rest of its time reading short TCP messages which are coming in at 6.5 kHz, and I think that will result in a non-trivial amount of time in drvAsynIPPort.  Some of it will be in the system Ethernet driver, network stack, etc.

Hi, Mark.

What does the "time" command show?

Lewis

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System