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Thread: Graphics card advice

  1. #26
    Member
    Registered: Apr 2002
    Location: Third grave from left.
    Quote Originally Posted by Sulphur View Post
    Vulkan's based on Mantle, which AMD created.
    Like i said - i doubt it gave them any advantage over a month or two. Now, years (well, barely), later it makes no difference. Mantle was made because all the alternatives (OGL, DX) were terrible (driver overhead / inability for an app to say what it wants to do) at the time and AMD smelled an opportunity which they took (especially as AMD implementation for thous alternatives was really-really terrible [less so for DX for reasons already mentioned] in comparison to Nvidia). Mantle removed that mess - and Vulkan / DX12 did the same. BECAUSE they can. Because the hardware is more-or-less the same and the wast majority of the abstractions are just pointless hindrances for everyone (Unification of sorts. A process i remember people noting ~10+ years ago and it never stopped).

    A thin and direct driver layer can not have favorites. AMD does like to use Mantle in its Vulkan ads - because the average Tom does not understand any of it anyway. It is meaningless.

    Nvidia is not in the business of paying favors to competitors - quite the opposite, they are the biggest assholes around. Vulkan is not Mantle either - it is an common hardware abstraction which most notably contains core (for Vulkan) stuff for tile based devices (phones etc). Something that is completely absent from Mantle.

    Quote Originally Posted by Sulphur View Post
    Anyway, take a look see for yourself: https://www.tomshardware.com/reviews...64,5173-8.html
    Could not find anything even remotely relevant there :/. I am not terribly familiar with that mammoth-of-a-site. Maybe i do not know where to look.

    All i found was this quote: "Although Nvidia’s performance under Vulkan is much improved, AMD continues to dominate in Doom.".

    The first part of that said absolutely nothing about Vulkan implementation quality between the two - to their credit it does not pretend to. It is just a statement of fact and exactly matches what one would expect to be the case. Even so, i could not find what the statement is based on (i guess it directly addresses the improvements from switching to Vulkan).

    The second part i have no idea what it is trying to say or what it is based on (or it is just too stupid for me to easily accept the idiocy it seems to portray). Could not find anything on the site to clarify what it is supposed to mean.

    ----------------
    A few words about GPU performance.

    It is a function of:
    * GPU capabilities (inc. processing power)
    * Driver capabilities and overhead (inc. host caps/etc ... which is not relevant here, so i omit them from now on)
    * User overhead.

    Lets call them G, D and U for short and give them weights. A few illustrative out-of-my-ass-but-representible numbers:

    Ancient OGL: no-one cares.

    Older OGL: G:5 D:21 U:3 (also known as dentistry using the anal approach)

    Basically the driver has to literately reverse engineer on the fly what actually needs to be done and predict it ahead of time. Common side effect is that GPU is bored out of its mind as the driver/user cannot feed it enough work and it is just idling around. In the past it did not matter as the GPU was too slow to keep up anyway.

    Newer OGL has improved a lot (if you use only the right stuff): G:13 D:9 U:2
    AMD: G:12 D:12 U:2
    Nvidia: G:13 D:8 U:2

    Improved, but not completely fixed. But if you tread carefully then you can feed the GPU reasonably well most of the time while sacrificing noticeable amount of CPU time (assuming you can afford to do so).

    Vulkan/Mantle/DX12 remove a lot of the crap: G:15 D:2 U:1
    AMD, Nvidia: essentially the same (AMD has more restrictions, gradually getting rid of them would help i guess, but not much room for improvement either way. Iirc AMD had pretty poor parallelization for Vulkan [interleaving GPU work] ... don't remember. Was not relevant for me at the time).

    If your app was not driver/user overhead bound then none of them will be of any help at all.

    ----------
    Finding out the quality of Vulkan/DX12 implementation is rather difficult, as what you want is to extract the weight of D from G+D+U when D is very low (and scale thous by the effects of pipeline bubbles). Much easier to do that for older OGL as D weight is rather huge and often to the point that you can directly measure idle time of G (which should and usually is 0 or thereabout on newer APIs)

    It is hard for Nvidia to improve in doom (OGL vs Vulkan) as their OGL was not shit to begin with.
    It is easy for AMD to improve in doom as their OGL was and is shit in comparison.

    Ie. switching to Vulkan will expectedly show small gains for Nvidia and big gains for AMD. Also: AMD gains will naturally rise faster than Nvidia as new GPUs come out and OGL overhead affects AMD more.

    This is the core of the common misunderstanding (which seems to always involve Doom).

    Quote Originally Posted by Sulphur View Post
    ... but last time they disappeared up their own real-time raytracing butthole - it was called Larrabee ...
    Oh, right. Completely forgot that. That whole project was just perplexing.

    I hope intel gets something useful done this time.

  2. #27
    Chakat sex pillow
    Registered: Sep 2006
    Location: not here
    Not talking about API quality or ease of implementation, zombe. Just raw hardware performance and benchmarks compared on a per-GPU, per-API level. Analysis of driver-level implementation is not something a hardware site would normally do, and I'm unaware of a site that actually does that, though I'd love to read up on it.

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