The speed of uploading textures seems slow.

[robotech_er]

Hi,Aleksandar, I have remove the loop and add a trivial rendering, and move the codes for measuring to make them contain exactly the glTexSubImage() func,like this:

 
 
 
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo1);
    glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
 
 
    glBindTexture( GL_TEXTURE_2D, tex1 );
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo1);
 
 
    //--------------codes for timing---------------------------------------start
    GLuint query;
    glGenQueries(1, &query);
    glBeginQuery(GL_TIME_ELAPSED,query);
    //---------------------------------------------------------------------end
    glTexSubImage2D( GL_TEXTURE_2D, 0, 0, 0,tex1_width,tex1_height,GL_RED_INTEGER,GL_UNSIGNED_INT,0); //where the data transfer occurs
    DrawSomePoints();
    //-----------codes for timing--------------------------------------------start
    glEndQuery(GL_TIME_ELAPSED);
    GLuint elapsed_time;
    glGetQueryObjectuiv(query, GL_QUERY_RESULT, &elapsed_time);
    glDeleteQueries(1, &query);
    float time_ms = elapsed_time/1000000.0f;
    LogTime( time_ms ); //write time_ms to a log file.
    //-----------------------------------------------------------------------end
 
 
 
 
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);
 
 
    Render();
 
 
    //remap the buffer
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo1);
    glBufferData(GL_PIXEL_UNPACK_BUFFER, buffersize, 0, GL_STREAM_DRAW);
    pBufferData = (byte*)glMapBuffer(GL_PIXEL_UNPACK_BUFFER,GL_WRITE_ONLY);
    //pBufferData is a global variable, it will be refilled in another thread which focus on I/O.
 
 
    glBindBuffer(GL_PIXEL_UNPACK_BUFFER, 0);

But, the result turns out to be the same as the original, only differs 3-4 ms of transferring 200 M textures. Maybe i should find a new computer......I will continue to try.Thanks for your kind help.

[Aleksandar]

What I tried to achieve is to make you realize what's really happening, not to boost the speed.
I've overseen that you are uploading data in a separate thread. Do you have an adequate synchronization?

In order to get better performance you need two PBOs. A separate thread should fill one, while another is used for transferring to graphics memory and for drawing. But, you should fill data between glTexImage2D() and drawing to have an effect. In the best case, a buffer refill should be done in the same procedure (not in the separate thread) and should last exactly the same time as data transfer. In your case Render() waits for texture to be downloaded before executes, so you have no benefits of using PBO (just disable PBO, and use glTexSubImage() with a real pointer to check this; I think you'll get marginally worse results).

Also, transferring a 200[MB] texture in a single frame is not feasible. 200[MB] * 60[1/s] = 12[GB/s]
Your problem is not in a transfer speed, but in the wrong way of texture update. The texture should be broken into smaller pieces, and update one at the time. 20-30 [MB/frame] is something you should stick to.