使用OProfile分析OpenCV

Question

我有一个基本的OpenCV程序：

#include <iostream>
#include "opencv2/opencv.hpp"

int main(){

    std::cout<<"Reading Image..."<<std::endl;
    cv::Mat img = cv::imread("all_souls_000000.jpg", cv::IMREAD_GRAYSCALE);
    if(!img.data)
        std::cerr<<"Error reading image"<<std::endl;
    return 0;
}

它创建了可执行的ReadImage。我想使用OProfile对其进行分析。但是，运行：

operf ./ReadImage > ReadImage.log

返回：

Kernel profiling is not possible with current system config.
Set /proc/sys/kernel/kptr_restrict to 0 to collect kernel samples.
operf: Profiler started
* * * * WARNING: Profiling rate was throttled back by the kernel * * * *
The number of samples actually recorded is less than expected, but is
probably still statistically valid.  Decreasing the sampling rate is the
best option if you want to avoid throttling.

Profiling done.

为什么会发生这种情况？分析OpenCV的最佳方法是什么？

Answer 1

我能够在一个opencv应用上运行operf，结果是，这就是你要找的吗？

Profiling started at Tue Jan 31 16:52:48 2017
Profiling stopped at Tue Jan 31 16:52:53 2017

-- OProfile/operf Statistics --
Nr. non-backtrace samples: 337018
Nr. kernel samples: 5603
Nr. user space samples: 331415
Nr. samples lost due to sample address not in expected range for domain: 0
Nr. lost kernel samples: 0
Nr. samples lost due to sample file open failure: 0
Nr. samples lost due to no permanent mapping: 0
Nr. user context kernel samples lost due to no app info available: 0
Nr. user samples lost due to no app info available: 0
Nr. backtraces skipped due to no file mapping: 0
Nr. hypervisor samples dropped due to address out-of-range: 0
Nr. samples lost reported by perf_events kernel: 0