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Mali 400 - Video memory available

Jean-Georges Levieux
Note: This was originally posted on 6th September 2012 at http://forums.arm.com

Hello,

We are developping a 3D game on a platform that has a Mali-400 MP4. I have a question about the video memory really available: the global chip has about 1go of memory (we can do 11 new of 100Mb each before to get a NULL pointer) but the memory available for graphics data seems quite low. Here is the code we used to check the available memory for both texture and VBO (tested seperatly):

// Vbo memory test.
    while (CheckGLError("Flush before VBO") == true); // Flush all previous errors.
    int const nSizeVBuffer = 512*1024;
    static char pDataVBuffer[nSizeVBuffer];
    int nNbVBO = 0;
    do
    {
        GLuint nVBufferID = 0;
        glGenBuffers( 1, &nVBufferID );
        glBindBuffer( GL_ARRAY_BUFFER, nVBufferID);
        glBufferData( GL_ARRAY_BUFFER, nSizeVBuffer, pDataVBuffer, GL_STATIC_DRAW);

        nNbVBO++;
        CPrintf::AddTextFile("Generate VBO %d (%d)\n", nNbVBO, nVBufferID);
    } while (CheckGLError("VBO Loading") == false);

// Here we "transfer" about only 70Mbytes before the GLerror.

// Texture memory test.
    while (CheckGLError("flush before Textures") == true); // Flush all previous errors.
    int const nW = 256;
    int const nH = 256;

    static char pTabPixel[nW * nH * 4];
    int nNbTexLoaded = 0;
    do
    {
        GLuint nTexId;

        glGenTextures ( 1, &nTexId);
        glBindTexture ( GL_TEXTURE_2D, nTexId);

        CPrintf::AddTextFile("Generate texture %d (%d)\n", nNbTexLoaded, nTexId);

        glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, nW, nH, 0, GL_RGB, GL_UNSIGNED_BYTE, pTabPixel);

        nNbTexLoaded++;

    } while (CheckGLError("Texture loading") == false);

// Here we "transfer" about only 90Mbytes before the GLerror.

So, in the best case it seems we have less than 100Mb of memory available for texture, vbo and ibo.

Does it seems a "normal" behavior or do we miss something? Could it be specific to the platform we are developping on (don't ask which one I cannot say)? Is there any way to have more "graphic" memory on Mali GPU?

Thank you in advance for your answers....

Regards,




Parents
  • Note: This was originally posted on 7th September 2012 at http://forums.arm.com

    Hello,

    Thank you for the answer.

    Unfortunately we are not building the driver, it's done by the vendor and linked dynamically at the launch of the application (we do not even have the lib files and we cannot change them by any way).

    Just to have an additionnal information to talk with the vendor: does it means that when memory is allocated for the GPU it's not more available for the system (CPU)? So, if you need a lot of system memory for CPU usage you have to limit the GPU memory allocated in the driver? The memory cannot be shared as it's possible on some other GPU/System?

    Regards,

Reply
  • Note: This was originally posted on 7th September 2012 at http://forums.arm.com

    Hello,

    Thank you for the answer.

    Unfortunately we are not building the driver, it's done by the vendor and linked dynamically at the launch of the application (we do not even have the lib files and we cannot change them by any way).

    Just to have an additionnal information to talk with the vendor: does it means that when memory is allocated for the GPU it's not more available for the system (CPU)? So, if you need a lot of system memory for CPU usage you have to limit the GPU memory allocated in the driver? The memory cannot be shared as it's possible on some other GPU/System?

    Regards,

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