Re: [Gems-users] Time spent in synchronization

[Hemayet Hossain <hossain@xxxxxxxxxxxxxxxx>]

Hi Dan,
I have collected the time through RUBY_CYCLES also. For that I have passed the binded proc id (kept in an array in program) with Magic calls for start and finish of lock/barriers calls and used that proc id for keeping track of which proc is in synchronization and which one is not. Do you think my approach is wrong?

Thanks,
Hemayet

Dan Gibson wrote:

gethrtime() is bogus under simulation. Solaris's view of time is 
horribly skewed under Simics alone or Simics+Ruby. Try measuring using 
RUBY_CYCLES instead.

Hemayet Hossain wrote:
  

Hi All,
I am simulating some splash2 benchmarks by using ruby with simics 2.2.19 
(Solaris 10) and to characterize the time spent in synchronization, I 
have instrumented the synchronization calls like locks and barrier. I 
have binded each thread to a specific processor (one-to-one) and 
collecting the time by calling high resolution timer gethrtime().  In 
real machine run (having 16 processors) for 16 threads I get around 19% 
time spent on synchronization for a program. If I run the same program 
in simics without ruby, I also get similar percentage of time spent in 
synchronization.

But If I run the same program in simics with ruby, the time spent in 
synchronization is much higher (goes around 75% of total).  I have 
collected the time from both programs and from ruby. Both are getting 
almost same percentage number. I am using MESI_SCMP_directory like 
protocol having 2 cycles for L1 and 14 cycles for L2 access.

Does anyone have any idea what's going on? What wrong with my setup? I 
would really appreciate your reply.
Thanks,
Hemayet

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