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counting L1 cache misses with PAPI_read_counters gives unexpected results

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问题 I am trying to use PAPI library to count cache misses. cache hit performance counter is not available on my hardware, that's why I am trying to determine cache hits with no cache misses. I am trying few things. First version of my code is this: int numEvents = 2; long long values[2]; int events[2] = {PAPI_L1_DCM, PAPI_L2_TCM}; if (PAPI_start_counters(events, numEvents) != PAPI_OK ) // !=PAPI_OK printf("PAPI error: %d\n", 1); for(int i=0; i < arr_size; i++) { array[i].value = 1; } _mm_mfence()

How to use PAPI periodically for performance measurements

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问题 I want to analyze system's performance for my application using PAPI api in C. The general structure is that -- Initialize PAPI -- Initialize counters of interest -- start counters -- run main logic of the application -- end counters and read values I want to read the counters periodically say every 1 second instead of reading the final values at the end of the application. does the PAPI output give the aggregate values at end of program execution like the total number of L2 cache misses

How to fix libpapi.so.* cannot open shared object file when running (py)COMPSs with tracing?

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问题 When I try to run some COMPSs application with the tracing system activated I get the following error: libpapi.so.5.3.0.0 cannot open shared object file I am using ubuntu and I have installed COMPSs from the packages with apt-get. To launch the application I use: runcompss --tracing --lang=python name_application.py I already installed the PAPI libraries with: apt-get install papi-tools libpapi-dev EDIT: I am using version 1.4 回答1: The tracing system can not find your PAPI installation

Why does Perf and Papi give different values for L3 cache references and misses?

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问题 I am working on a project where we have to implement an algorithm that is proven in theory to be cache friendly. In simple terms, if N is the input and B is the number of elements that get transferred between the cache and the RAM every time we have a cache miss, the algorithm will require O(N/B) accesses to the RAM. I would like to show that this is indeed the behavior in practice. To better understand how one can measure various cache related hardware counters, I decided to use different

Why does Perf and Papi give different values for L3 cache references and misses?

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I am working on a project where we have to implement an algorithm that is proven in theory to be cache friendly. In simple terms, if N is the input and B is the number of elements that get transferred between the cache and the RAM every time we have a cache miss, the algorithm will require O(N/B) accesses to the RAM. I would like to show that this is indeed the behavior in practice. To better understand how one can measure various cache related hardware counters, I decided to use different tools. One is Perf and the other is the PAPI library. Unfortunately, the more I work with these tools,