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  • #21
    Originally posted by gens View Post
    (disclaimer: i'm not an expert)
    i'm guessing here
    you are thinking about absolute efficiency

    thing is gpu's are nowadays just a bunch of compute units orchestrated by a control unit (theres more ofc)
    compute units are simple things
    with that kind of design gpu's are not limited to doing disk cleanup tools just one specific kind of "rendering"
    (rendering 3D is just a bunch of mathematical transforms with some logic in the mix)

    so a gpu driver is basically a state machine that says to the hardware (firmware in this case) what should be done


    also about the cpu part in it
    even in a case of something simple like a desktop or a window with some buttons or something you still need the logic behind it

    like when you move a window
    you have to calculate where it is moved
    check, based on rules, things like if you move it to an edge do you flip to the next virtual desktop (etc)

    but that is simple
    in complex graphics for example you don't want the gpu to draw the whole huge world
    so you cull everything not seen
    you do it on the cpu because you have to know in advance what you will be rendering (to not send textures when not needed, vertices, etc.)
    (this is also required for a desktop if you want lower gpu memory usage)


    still i like the idea of directly controlling the gpu
    i read something that in the future (or maybe even now in new opengl) you will be able to get a pointer in gpu memory

    also i think gpus are going in the direction of having a dedicated cpu (like ARM or something) on them that would control it
    imagine you could write full fledged programs to run on a massively parallel gpu (like semi touring-complete shaders)

    in my eyes the future looks bright in the gpu department

    edit: in short; they are complicated so they don't become even more complicated, but they are simplifying slowly (in general design)
    my cheap laptop have Intel HD Graphics 2500. good enough for playing many FPS and RTS titles released before 2008 at medium details.

    Comment


    • #22
      Take a look at the slides from AMD's true audio, which bypasses the gpu/cpu and instead uses a specific hardware that's built in to raise overall performance. Mantle let's you bypass the cpu for setting things up. Anyways those slides will show you how much each things costs to process.

      Comment


      • #23
        Originally posted by profoundWHALE View Post
        ...which bypasses the gpu/cpu and instead uses a specific hardware that's built in to raise overall performance.
        please don't, just don't talk about audio processing
        it's an area with many many people who don't know about it (and some are "smart" non the less, that's why i don't call myself an audiophile)
        here, a low pass FIR filter
        i think it's 32 tap, cant remember

        Code:
        format ELF64 executable
        entry start
        
        align 16
        segment readable writeable
        
        samples equ 1024
        
        align 16
        buff_in: rw samples*2
        align 16
        buff_out: rw samples*2
        
        ; 2^16 = 1.0
        align 16
        coefficients:
        
        dw 5
        dw 14
        dw 35
        dw 57
        dw 39
        dw -76
        dw -328
        dw -677
        dw -945
        dw -828
        dw 16
        dw 1799
        dw 4428
        dw 7441
        dw 10109
        dw 11680
        dw 11680
        dw 10109
        dw 7441
        dw 4428
        dw 1799
        dw 16
        dw -828
        dw -945
        dw -677
        dw -328
        dw -76
        dw 39
        dw 57
        dw 35
        dw 14
        dw 5
        
        dw 705
        dw 1240
        dw 1434
        dw 1169
        dw 456
        dw -550
        dw -1576
        dw -2287
        dw -2367
        dw -1609
        dw 25
        dw 2377
        dw 5106
        dw 7760
        dw 9862
        dw 11024
        dw 11024
        dw 9862
        dw 7760
        dw 5106
        dw 2377
        dw 25
        dw -1609
        dw -2367
        dw -2287
        dw -1576
        dw -550
        dw 456
        dw 1169
        dw 1434
        dw 1240
        dw 705
        
        rq 10 ;just in case
        tmp rq 100
        
        sys_read equ 0
        sys_write equ 1
        sys_exit equ 60
        
        
        align 16
        segment readable executable
        
        start:
        
        xorps xmm7, xmm7
        xorps xmm6, xmm6
        xorps xmm5, xmm5
        xorps xmm4, xmm4
        xorps xmm3, xmm3
        xorps xmm2, xmm2
        xorps xmm1, xmm1
        xorps xmm0, xmm0
        
        mov [tmp], rdx
        mov [tmp+8], rdx
        
        filter:
        
        mov rdx, samples*2*2
        mov rsi, buff_in
        mov rdi, 0
        mov rax, sys_read
        syscall
        cmp rax, 0
        jz end_fir
        
        xor rax, rax
        
        mov rcx, samples
        loopy:
        movaps xmm12, [coefficients]
        movaps xmm13, [coefficients+16*1]
        movaps xmm14, [coefficients+16*2]
        movaps xmm15, [coefficients+16*3]
        mov edx, [rax+buff_in] ;dx = left channel sample
        mov esi, edx
        shr esi, 16 ;si = right channel sample
        
        ; left channel delay line
        pslldq xmm3, 2
        movaps xmm10, xmm2
        psrldq xmm10, 2*7
        orpd xmm3, xmm10
        
        pslldq xmm2, 2
        movaps xmm10, xmm1
        psrldq xmm10, 2*7
        orpd xmm2, xmm10
        
        pslldq xmm1, 2
        movaps xmm10, xmm0
        psrldq xmm10, 2*7
        orpd xmm1, xmm10
        
        pslldq xmm0, 2 ;bytes
        movzx rdx, dx
        movq xmm10, rdx
        orpd xmm0, xmm10
        
        ; right channel delay line
        pslldq xmm7, 2
        movaps xmm10, xmm6
        psrldq xmm10, 2*7
        orpd xmm7, xmm10
        
        pslldq xmm6, 2
        movaps xmm10, xmm5
        psrldq xmm10, 2*7
        orpd xmm6, xmm10
        
        pslldq xmm5, 2
        movaps xmm10, xmm4
        psrldq xmm10, 2*7
        orpd xmm5, xmm10
        
        pslldq xmm4, 2
        movq xmm10, rsi
        orpd xmm4, xmm10
        
        
        
        
        movaps xmm8, xmm12
        movaps xmm9, xmm13
        movaps xmm10, xmm14
        movaps xmm11, xmm15
        
        
        pmaddwd xmm12, xmm0
        pmaddwd xmm13, xmm1
        pmaddwd xmm14, xmm2
        pmaddwd xmm15, xmm3
        
        paddd xmm12, xmm14
        paddd xmm13, xmm15
        
        paddd xmm12, xmm13
        
        movhlps xmm13, xmm12
        paddd xmm12, xmm13
        
        movss xmm13, xmm12
        psrldq xmm12, 32
        paddd xmm12, xmm13
        
        
        
        pmaddwd xmm8, xmm4
        pmaddwd xmm9, xmm5
        pmaddwd xmm10, xmm6
        pmaddwd xmm11, xmm7
        
        paddd xmm8, xmm10
        paddd xmm9, xmm11
        
        paddd xmm8, xmm9
        
        movhlps xmm9, xmm8
        paddd xmm8, xmm9
        
        movss xmm9, xmm8
        psrldq xmm8, 32
        paddd xmm8, xmm9
        
        
        
        movd r10d, xmm12
        ;sal r10d, 3 ;overflow possibility unless compensated
        shr r10d, 16
        mov [rax+buff_out], r10w
        
        movq r10, xmm8
        ;sal r10d, 2
        shr r10d, 16
        mov [rax+buff_out+2], r10w
        
        add rax, 4
        dec rcx
        jnz loopy
        
        mov rdx, samples*2*2
        mov rsi, buff_out
        mov rdi, 1
        mov rax, sys_write
        syscall
        
        jmp filter
        
        end_fir:
        mov rax, sys_exit
        syscall
        bash-4.2# time ./example < hell.raw >hell2.raw

        real 0m2.206s
        user 0m0.129s
        sys 0m0.251s

        where hell.raw is a 64MB, ~6.25 minutes long, 44100Hz, 16bit stereo
        and most of that time is spent in read() and write()
        Last edited by gens; 04-28-2014, 07:59 AM.

        Comment


        • #24
          i think i c/p a testing version
          here is that i know is correct
          (phoronix... rly took me 30sec to realize)

          Code:
          format ELF64 executable
          entry start
          
          align 16
          segment readable writeable
          
          samples equ 1024
          
          align 16
          buff_in: rw samples*2
          align 16
          buff_out: rw samples*2
          
          ; 2^16 = 1.0
          align 16
          coefficients:
          
          dw 5
          dw 14
          dw 35
          dw 57
          dw 39
          dw -76
          dw -328
          dw -677
          dw -945
          dw -828
          dw 16
          dw 1799
          dw 4428
          dw 7441
          dw 10109
          dw 11680
          dw 11680
          dw 10109
          dw 7441
          dw 4428
          dw 1799
          dw 16
          dw -828
          dw -945
          dw -677
          dw -328
          dw -76
          dw 39
          dw 57
          dw 35
          dw 14
          dw 5
          
          rq 10 ;just in case
          tmp rq 100
          
          sys_read equ 0
          sys_write equ 1
          sys_exit equ 60
          
          
          align 16
          segment readable executable
          
          start:
          
          xorps xmm7, xmm7
          xorps xmm6, xmm6
          xorps xmm5, xmm5
          xorps xmm4, xmm4
          xorps xmm3, xmm3
          xorps xmm2, xmm2
          xorps xmm1, xmm1
          xorps xmm0, xmm0
          
          mov [tmp], rdx
          mov [tmp+8], rdx
          
          filter:
          
          mov rdx, samples*2*2
          mov rsi, buff_in
          mov rdi, 0
          mov rax, sys_read
          syscall
          cmp rax, 0
          jz end_fir
          
          xor rax, rax
          
          mov rcx, samples
          loopy:
          movaps xmm12, [coefficients]
          movaps xmm13, [coefficients+16*1]
          movaps xmm14, [coefficients+16*2]
          movaps xmm15, [coefficients+16*3]
          mov edx, [rax+buff_in] ;dx = left channel sample
          mov esi, edx
          shr esi, 16 ;si = right channel sample
          
          ; left channel delay line
          pslldq xmm3, 2
          movaps xmm10, xmm2
          psrldq xmm10, 2*7
          orpd xmm3, xmm10
          
          pslldq xmm2, 2
          movaps xmm10, xmm1
          psrldq xmm10, 2*7
          orpd xmm2, xmm10
          
          pslldq xmm1, 2
          movaps xmm10, xmm0
          psrldq xmm10, 2*7
          orpd xmm1, xmm10
          
          pslldq xmm0, 2 ;bytes
          movzx rdx, dx
          movq xmm10, rdx
          orpd xmm0, xmm10
          
          ; right channel delay line
          pslldq xmm7, 2
          movaps xmm10, xmm6
          psrldq xmm10, 2*7
          orpd xmm7, xmm10
          
          pslldq xmm6, 2
          movaps xmm10, xmm5
          psrldq xmm10, 2*7
          orpd xmm6, xmm10
          
          pslldq xmm5, 2
          movaps xmm10, xmm4
          psrldq xmm10, 2*7
          orpd xmm5, xmm10
          
          pslldq xmm4, 2
          movq xmm10, rsi
          orpd xmm4, xmm10
          
          
          
          
          movaps xmm8, xmm12
          movaps xmm9, xmm13
          movaps xmm10, xmm14
          movaps xmm11, xmm15
          
          
          pmaddwd xmm12, xmm0
          pmaddwd xmm13, xmm1
          pmaddwd xmm14, xmm2
          pmaddwd xmm15, xmm3
          
          paddd xmm12, xmm14
          paddd xmm13, xmm15
          
          paddd xmm12, xmm13
          
          movhlps xmm13, xmm12
          paddd xmm12, xmm13
          
          movss xmm13, xmm12
          psrldq xmm12, 32
          paddd xmm12, xmm13
          
          
          
          pmaddwd xmm8, xmm4
          pmaddwd xmm9, xmm5
          pmaddwd xmm10, xmm6
          pmaddwd xmm11, xmm7
          
          paddd xmm8, xmm10
          paddd xmm9, xmm11
          
          paddd xmm8, xmm9
          
          movhlps xmm9, xmm8
          paddd xmm8, xmm9
          
          movss xmm9, xmm8
          psrldq xmm8, 32
          paddd xmm8, xmm9
          
          
          
          movd r10d, xmm12
          ;sal r10d, 3 ;overflow possibility unless compensated
          shr r10d, 16
          mov [rax+buff_out], r10w
          
          movq r10, xmm8
          ;sal r10d, 2
          shr r10d, 16
          mov [rax+buff_out+2], r10w
          
          add rax, 4
          dec rcx
          jnz loopy
          
          mov rdx, samples*2*2
          mov rsi, buff_out
          mov rdi, 1
          mov rax, sys_write
          syscall
          
          jmp filter
          
          end_fir:
          mov rax, sys_exit
          syscall

          Comment


          • #25
            Originally posted by Daktyl198 View Post
            I don't get this either... why can't we map the API calls to the specific hardware at boot or through a function (for hot-swapping/other GPU changes) and store the result, that way we don't spend precious CPU cycles translating all the time?
            Because GPU design changes over time, and if you hardcoded everything, the API would break every single time the HW it ran on changed. You also ignore the quite possible case of multiple-GPU's, or even non-GPU cards that can run the OGL API (ASIC's and the like).

            You also have the somewhat substantial driver layer to manage the HW resources, which also saps performance and is probably THE performance killer on weaker CPU's. Thats what Mantle/DX12 is attempting to solve going forward.

            The final problem, at least for OGL, is the API is aged, doesn't reflect how the HW actually works anymore, and simply doesn't play well with newer programming methodologies (Object Oriented, OGL is not).

            Comment


            • #26
              Originally posted by Daktyl198 View Post
              I understand that a lot of computations are done on the CPU, then the results are sent to the GPU. I was talking more about stuff like this though:

              Watching a 1080p video normally, and watching a 1080p video with "hardware acceleration".
              I assume the first means that all decoding and graphics processing is done on the CPU (assuming a non-OGL rendering method) while the second means using the GPU for both operations. If this is true, why wouldn't the GPU be used in the first place? Since it's obviously made for tasks such as these, vs the CPU which (for the most part) is not.
              Not every GPU can do this. What about new encoding formats on old GPUs? What if the user is running some other GPU heavy task at the same time; would it be better to let the CPU handle the video decoding instead?

              On a general purpose PC, you can NOT assume you have access to all computer resources. You can NOT assume full HW support.

              Take a look at the slides from AMD's true audio, which bypasses the gpu/cpu and instead uses a specific hardware that's built in to raise overall performance. Mantle let's you bypass the cpu for setting things up. Anyways those slides will show you how much each things costs to process.
              But you tie yourself to a SPECIFIC HW specification. Take Mantle; its designed for only GCN GPU's. What happens when GCN reaches EOL and AMD has to replace it? Woops, every game that used Mantle now needs to patch itself, because the assumptions made about the HW design no longer hold true.

              Hence the advantage and disadvantage of higher level API's: You can abstract everything, and keep support, in theory, forever. The downside is, this easily doubles the time to complete any specific task, due to said abstraction. If you want speed, you go to lower level API's. If you want support, you go to higher level API's.

              Hence why we have consoles.
              Last edited by gamerk2; 04-28-2014, 10:58 AM.

              Comment


              • #27
                Originally posted by gamerk2 View Post
                Take Mantle; its designed for only GCN GPU's. What happens when GCN reaches EOL and AMD has to replace it? Woops, every game that used Mantle now needs to patch itself, because the assumptions made about the HW design no longer hold true.
                It's not designed for *only* GCN GPUs -- it's more correct to say that the HW capabilities of GCN GPUs represent the minimum requirement.

                Comment


                • #28
                  Originally posted by bridgman View Post
                  It's not designed for *only* GCN GPUs -- it's more correct to say that the HW capabilities of GCN GPUs represent the minimum requirement.
                  Nope. When you make that low a level API, you *are required* to expose the lower level details of how the GPU operates in order to create a working driver. Every time the HW capabilities change, you are going to have to tear apart the API to support the newer architecture.

                  I still remember the days when games shipped with four different graphics drivers and two or three audio drivers. I do NOT want to go back to those days.

                  Comment


                  • #29
                    Originally posted by gamerk2 View Post
                    Nope. When you make that low a level API, you *are required* to expose the lower level details of how the GPU operates in order to create a working driver. Every time the HW capabilities change, you are going to have to tear apart the API to support the newer architecture.

                    I still remember the days when games shipped with four different graphics drivers and two or three audio drivers. I do NOT want to go back to those days.
                    Agreed, but Mantle is not that low level.

                    Comment


                    • #30
                      Originally posted by gamerk2 View Post
                      Nope. When you make that low a level API, you *are required* to expose the lower level details of how the GPU operates in order to create a working driver. Every time the HW capabilities change, you are going to have to tear apart the API to support the newer architecture.

                      I still remember the days when games shipped with four different graphics drivers and two or three audio drivers. I do NOT want to go back to those days.
                      No. Mantle only requires GCN because it requires certain hw features that we not available on older asics.

                      Comment

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