I have a riddle for you.
Given a system with real time processes.
One process (process M) monitors some quantity (say, temperature) and
makes measured values of the quantity available for another process
(process A).
Process A retrieves the measured temperature once in a while and takes
some acti
On 13/04/11 16:07, Omer Zak wrote:
The riddle:
1. If the operating system being used is Linux, what other mechanisms
(besides turning off interrupts) are available to single-processor
systems to accomplish this?
2. If the system has a multi-core processor or several processors, which
low overhead
A full fledged queue would force the consuming process (process A) to
read and process all data written by the producing process (process M)
even when process A needs only the most recent value whenever it reads
process M's data.
On Wed, 2011-04-13 at 16:21 +0300, Shachar Shemesh wrote:
> On 13/04
On 13/04/2011 15:41, Omer Zak wrote:
A full fledged queue would force the consuming process (process A) to
read and process all data written by the producing process (process M)
even when process A needs only the most recent value whenever it reads
process M's data.
On Wed, 2011-04-13 at 16:21 +
Hi Omer,
On Wed, Apr 13, 2011 at 04:07:42PM +0300, Omer Zak wrote:
> The system has several such processes, so it is desirable to have an
> inter-process mechanism having the absolute minimum overhead for
> unidirectional data transfers from measuring processes (like process M)
> to action taking
On 04/13/2011 09:41 AM, Omer Zak wrote:
A full fledged queue would force the consuming process (process A) to
read and process all data written by the producing process (process M)
even when process A needs only the most recent value whenever it reads
process M's data.
I forgot how this scheme
On Wed, 2011-04-13 at 16:40 -0400, Ori Berger wrote:
> On 04/13/2011 09:41 AM, Omer Zak wrote:
>
> > A full fledged queue would force the consuming process (process A) to
> > read and process all data written by the producing process (process M)
> > even when process A needs only the most recent v
On 04/13/2011 05:04 PM, Omer Zak wrote:
If the counter is one byte wide, then any updates to it would be atomic
by definition (of course, the context is that only process M ever
modifies it).
While that is true, I was wrong in asserting that "atomic" is enough. It
needs to be ordered with res
Omer,
you did not specify the timing constraints you have, so the very basic
thing mechanism is to use a posix semaphore for mutual exclusion access
to this memory.
this will work both on single-core and multi-core systems.
note that disabling interrupts is not possible from user space - so it
