On 12/27/2022 2:48 AM, 李南松 wrote:
Hi Eliot Moss,Thanks for your reply. I am generating Checkpoint for SPEC2017. Do I need to regenerate my BBV file under N cpus system? There is a condition here that the simpoint_profile (BBV) cannot be generated when n > 1. $vim ./configs/example/fs.py +210 205 # Sanity check 206 if options.simpoint_profile: 207 if not ObjectList.is_noncaching_cpu(TestCPUClass): 208 fatal("SimPoint generation should be done with atomic cpu") 209 if np > 1: 210 fatal("SimPoint generation not supported with more than one CPUs") How should I generate my BBV file?
Clearly, with one cpu. The BBV file simply says how many times each block of code is executed within a given time window. I believe that if you take k simpoints, that implies k time windows. So it's just gathering statistics. Separately you run simulations that determine the amount of time the blocks take and the BBV is then used to extrapolate the total amount of time without running a detailed simulation of everything. It is not clear to me that the methodology works with multiple CPUs, but it's not something I've used or have deep knowledge of. (A quick glance on the web suggests that simpoints is a single-threaded technique.) Apparently there are other methods people have researched for multi-threaded applications. The hard thing there is that the different threads interact, even if only my their simultaneous impact on the memory system. So performance is hard to determined. Hope this helps -- EM _______________________________________________ gem5-users mailing list -- gem5-users@gem5.org To unsubscribe send an email to gem5-users-le...@gem5.org
