Re: LLM On vs ultra
Posted: 13 Apr 2020, 08:51
ULL is a queue control mechanism. This queue is the one that holds the frames that CPU just have rendered. If the GPU is faster than the CPU you will never have a queue as the GPU will finish its job before the CPU renders the next frame. It is also the same scenario when limiting into a stable value because your GPU time will be faster than the CPU Render time + sleep(). The Queue happens when the GPU is slower than the time it takes to receive a new frame. If you have a large queue you can maximize GPU utilization and have a small increment in the fps as the bottleneck will never wait for a frame but it also means that those frames have their GPU processing delayed. ULL acts like it was the value of 0 but in reality, it's a just in time delivery. It predicts when the GPU will finish the current work and then calculated the exact point where CPU should start rendering to deliver that frame just a little before the GPU is ready. GPU loads nearly 100% means it is not sleeping so it should be slower than the CPU. Do that make sense fit you?bapt337 wrote: ↑13 Apr 2020, 05:09Personnaly i didnt notice any benefit to use LLM ultra comapre to LLM ON in term of inputlag, even more in my scenario cpu never bottleneck casue frame are limited, and gpu also never used to the max, so i dont get the point to use LLM ultra compare to LLM = ON.andrelip wrote: ↑13 Apr 2020, 04:27I think that the author main point is to know the overhead of Low Latency Mode on Ultra for scenarios when it is not needed (bottlenecked by the limiter or CPU). I didn't find any significant difference on my tests so I just leave it on ultra on all cases.
Some people claim it adds significant input lag (many ms) but their methodology is not reliable in my option as they usually test input lag using events that depend on tickrate and network such as strafe or gunfire instead of instantaneous events of the engine like camera angle. Those tickrates are usually a bottleneck (7.8ms for a high quality 128 tickrate) and have other side-effects. You could have a huge difference in response if you cap at 127.5 or 128.5 depending on how the engine handles cmd throttling.
And i dont know how LLM=ULTRA can be usefull in cpu bound scenario? i mean, LLM=ULTRA= 0 pre rendered frame, so no buffer, then it should the most heavy for cpu, so if you already cpu bottleneck, and use LLM=ultra, hmmm....
On other hand i dont understand why LLM=ultra have to be used in gpu bound scenario, why couldnt it work with low gpu usage? cause if low gpu usage this mean its cpu limited? or framerate limited? in that case then LLM = ultra have to be used with unlocked fps? cause depending the game, uncapped fps will bound the gpu, but on CS GO for example, uncapped fps give cpu botleneck, so not good for LLM= ultra.
Sorry for all my odd question, this become a bit obsessional to me, i really want to know how it work from A to Z.