[Gems-users] Transactional Manager and Protocols

[Konstantinos Nikas <knikas@xxxxxxxxxxxxxxxxx>]

Hi all,

we are using LogTM to run some transactional versions of various graph 
algorithms.
More specifically we are simulating a 4-core machine using the 
MESI_CMP_filter_directory protocol and we create 2 threads which we bind 
on 2 of the processors. We don't config any of the chip/memory hierarchy 
options, we just use the default values. When the code is executed, the 
stats report 0 aborts and of course the products of the algorithms are 
wrong.

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?
Kind regards,

Kostis