[ECOS] Suitability of eCos

James Dabbs JDabbs@TGA.com
Tue Jan 16 07:52:00 GMT 2001

Generally speaking, when your real-time threads are using up their entire
timeslice, you are probably out of CPU bandwidth.  Timeslices are usually
not used for real-time response, but for lower-priority supervisory threads
with less demanding requirements.  It sounds like you need to use a delta
timer queue driven from a HW high-precision timer.  While the OS is
"ticking" away timeslices once every 100mS, this timer is scheduling
activity on a microsecond basis.

-----Original Message-----
From: Grant Edwards [ mailto:grante@visi.com ]
Sent: Tuesday, January 16, 2001 10:31 AM
To: Pamulapati, Indrasena (CTS)
Cc: ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] Suitability of eCos

On Tue, Jan 16, 2001 at 03:19:17PM +0530, Pamulapati, Indrasena (CTS) wrote:

> What u say is right. As we decrease the tick duration the
> efficiency of the OS comes down because of the overhead
> involved in processing the tick.
> But my application requires tick duration as low as a
> 100microseconds. I need to address such low time resolutions.

That may not mean that you have to have an OS tick that small.
If your critical tasks are driven by interrupts, then the
length of the OS tick isn't particulary important -- it's
driven more by the resolution needed on things like the
timeouts you want when waiting for an event that doesn't

> I feel there should be some parameters of rtos's that have to
> be considered with reference to the application we are building
> before deciding the OS.

Of course there are.  But you are the only one who knows what
the most important factors are.  If you tell us what those
factors are, perhaps we can tell you how well eCos suits your

Grant Edwards

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