Trigger-based statistics dump

[qtt2]

Hi,

We have some statistics that are calculated at the end of simulation via simulationTerminating_(). For example, a cache.total_read_access of a cache is the sum of all cache.bank[0-7].read_access of its banks 0 to 7. When you use triggers (e.g., start and stop) to dump statistic report for a specific region, this stat does not get updated because simulationTerminating_() is not called at trigger points.

I can think of two possible options:

(1) In the report def yaml file, I define something like this

cache.bank*.read_access : read_access_$1

This prints out the read_access per banks, and I need to do a post-processing step to accumulate all read_access_[0-7] after the report gets generated. It would be nice if we can define a sum across all instances of cache.bank*.read_access in the report.

(2) In the simulator, call a function similar to simulationTerminating_() to accumulate partial stats at trigger points. I don't know if something like that already existing in the framework. If so, can someone point me to that?

Thanks,

Tuan

[klingaard]

Sorry for the delay -- been out of town.

For the first option, you should be able to create an expression in your report file like we do for Dhrystone MIPS calculation: https://github.com/riscv-software-src/riscv-perf-model/blob/8d187b22e95ac8490489fa3ed9f64a51faf42705/reports/dhry_report.yaml#L14

It's not elegant, but possible. Another option is to create a StatisticDef instance in your class that sums them up:

   // There are many constructors, using a simpler one
   sparta::StatisticDef cache_bank_sums_{getStatisticSet(), 
                                         "total_read_accesses_in_bank", // stat name
                                         getContainer(),  // stat context -- where the cache.bank*.read_access stats are
                                         R"( cache.bank1.stats.read_access + 
                                             cache.bank2.stats.read_access + 
                                             cache.bank3.stats.read_access` +
                                             cache.bank4.stats.read_access + 
                                             cache.bank5.stats.read_access + 
                                             cache.bank6.stats.read_access + 
                                             cache.bank7.stats.read_access)"};  // expression

The neat thing you can do here is to create the StatisticDef dynamically, during construction, and create the expression on the fly based on the number of banks.

For (2), if you use the StatisticDef class, it will work really well with triggers. It's only evaluated on triggers.

Hope this helps.