Re: [Gems-users] Transactional Manager and Protocols

[Konstantinos Nikas <knikas@xxxxxxxxxxxxxxxxx>]

Hi Jayaram,

thanks for the clarification.

So, any idea why we saw 0 aborts when we had g_PROCS_PER_CHIP=1 (which 
means that the system was unable to detect confilcts between the 
different R/W sets and our parallel code failed) and when we set 
g_PROCS_PER_CHIP=4 (our system had 4 procs) the problem went away and 
everything worked fine?

Kind regards,

Kostis

Jayaram Bobba wrote:
> > After some tests, we found out that for our benchmarks to work 
> > correctly, we need to set g_PROCS_PER_CHIP equal to the number of 
> > processors. Which makes sense, since MESI_CMP_filter_directory is 
> > described as a single-chip protocol. However, ti would be interesting to 
> > know if the problem is caused by a limitation of the Transactional 
> > Manager that it cannot check transactions across different chips? Or is 
> > it something that has to do with this specific coherence protocol, in 
> > which case if we used another protocol LogTM would work fine?  And of 
> > course can we use LogTM with the other protocols that are shipped with GEMS?
> >   
> >     
> No the transactional manager code is independent of the number
> of chips in the system. LogTM is supported only by the 
> MESI_CMP_filter_directory
> protocol...
>
> Jayaram
>
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