top shows very high cpu usage when waiting on V4l2MmapCapture::read

[mpromonet]

top shows very high cpu usage when waiting on V4l2MmapCapture::read

[mpromonet]

Hi amitv87,
Usually I use select before calling read, for instance in v4l2copy.cpp :

   tv.tv_sec=1;
   tv.tv_usec=0;
   FD_SET(videoCapture->getFd(), &fdset);
   int ret = select(videoCapture->getFd()+1, &fdset, NULL, NULL, &tv);
   if (ret == 1)
   {
        char buffer[videoCapture->getBufferSize()];
        int rsize = videoCapture->read(buffer, sizeof(buffer));
        ....

I see you find the xioctl is looping in an active loop that cause the 100% CPU. Probably the xioctl is a bad idea, if the device is not ready to read, it should return an error.

Regards,
Michel.

[amitv87]

Thanks Michel, had figured that out ;)