Finding the Performance Bottleneck

Discussion in 'Game Tweaks and Modifications' started by ElectronSpider, Nov 7, 2016.

  1. Edit: Solved, see post #5: http://forums.guru3d.com/showpost.php?p=5356613&postcount=5
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    I am very familiar with using MSI Afterburner with RivaTuner to pull up performance metric such as GPU usage, clock speed, cpu cores' usage, etc. What I do not understand is with a few games (2013+) is that the cpu usage for each core may never use more than 30% and the GPU usage stays around 80 - 85% with an unlocked framerate.

    My initial reaction was that a core responsible for the render thread must being used 100% (spread across multiple cores), but turning GPU bound settings down still improved performance. Also, note that even a game that was hard-locked to 60 fps by the game hovering around 53-55 fps when looking at many objects in the world, but would reach 60 when looking at the ground or sky.

    I am wondering what other cases could it be if the bottleneck is not from the CPU cores nor GPU nor VRAM usage. I wonder if newer games are reserving 15 - 20% of the GPU for Compute tasks or is it a DirectX 11 draw call limitation or is the GPU memory controller being taxed even though it's not using close to max VRAM? I noticed a youtube video where a youtuber who has the same GPU, but better CPU (2500K) is having the same symptoms of GPU usage staying around 80 -85%, while the CPU core usage was rather low (30% or less) with framerates fluctuating between 40 - 50 fps.
     
    Last edited by a moderator: Nov 9, 2016
  2. Raptorta

    Raptorta Member

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    I would try DSR to increase gpu only load and see if it increases gpu usage then lower my resolution to see if it increases cpu load and fps, the ratio could help you find the culprit.
     
  3. Thanks for the reply and suggestions! I decreased the resolution and increase the resolution, but in both cases the GPU usage stays around 80 - 85%. The interesting bit is that when I lower the resolution the GPU usage percentage decreases (60 - 70%), but the framerate does go up to 60 fps and CPU core usage is still low (around 30% for each core). Also, want to note, I'm not talking about all newer (2013+) games, but specific ones like Assassin's Creed Rogue/Blackflag and TombRaider 2013.

    Based on what I have observed, the bottleneck lies in the game engine implementation. It makes sense because some game engines are bad at making use of the hardware.
     
  4. -Tj-

    -Tj- Ancient Guru

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    I think its time to put that PII to sleep :nerd:

    Its most definitely Cpu and system ram bottleneck..
    PhenomII is fast but not fast enough.. From what I remember even C2Q @ 3.6Ghz ran faster and that bottlenecked my old 570GTX.

    I could raise resolution to put more load on gpu, but min fps stayed the same no matter what..
     

  5. I was not referring to the min fps nor all newer games (only a select few games). I understand that there can be minor dips in framerate and GPU usage possibly could go lower than 99% in short instances. I was referring to cases where no matter what I do the GPU usage stays at 80-85% all the time with AC Rogue and AC Blackflag with an unlocked framerate. I'll use PresentMon tool to tell me whether I am GPU or CPU bound, I would not be surprised if PresentMon said I was GPU bound with 80% GPU usage considering the very low CPU core usage.

    This is on the basis that if I was CPU bottlenecked in those two games then only reducing my resolution (purely GPU affected) would not improve my framerate, which I stated did improve average/max framerate by 10-15 fps (locking to 60 fps) when I lowered resolution 1 peg from 1920 to 1600, but GPU usage stayed around 80%. In addition, my system is balanced, the GTX 660 will a majority of the time bottleneck before the Phenom II x6, except in games like Civilization, where there is thousands of decisions and statistics the CPU has to calculate or keep track of for each set of moves.

    There is such thing as game engine/api bottlenecks. Problem is solved for me, I'll just lock those few games affected to 50 fps. /Thread
     

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