CPU time graph, what does it show?

S

salvasirignano

Registered
Please could someone explain exactly what the green graph and two purple bars in the CPU time graph mean?

I have a 2.33 GHz dual core ( I know, below the minimum :o I'm upgrading the CPU any day now hopefully)
and have been getting microstutters (when the thin purple line flows across to the right , see pic) and huge long pauses, sometime a few seconds, denoted by the aforementioned happening, as well as the thick purple bar moving all the way to the right.
I'm guessing the green one is CPU load vs time :p

Thanks in advance


View attachment 532
 
After some more testing, I can without a doubt say I...... have no clue what it does.... lol.:confused:

Any staff care to maybe chime in so I know what I'm looking at. I couldn't find any info on it in the folders. Thought maybe there was an explanation for it but can't seem to find anything.
 
Histograms are distributions of frame time. Bars are resource utilization. A full bar is full utilization (okay for graphics, not okay for physics). Green start with a G so that is Graphics, Purple starts with a P so that is for Physics.

Tall spikes mean the frame rate time is consistent around a given time. Obviously, the Physics histogram is inverted.
 
salvasirignano said:
...and have been getting microstutters (when the thin purple line flows across to the right , see pic)
Click to expand...

Yup, this is bad news. Basically whatever is causing the halt is causing the physics to 'back up', or not being run when it's supposed to be run. For every pixel in the purple histogram, the physics is being run late by that many milliseconds. You want a fairly thin purple line within a few pixels of the left edge, not scattered across the graph as in your example.

The graphics histogram, on the other hand, records how many milliseconds each frame took. It's okay to be somewhere in the middle, although too far to the right indicates slow framerate. We still want to see them in a consistent range, however, not a bunch of dots scattered off to the right which is related to graphics stuttering.

Additionally, it might help you to understand the graphs with the knowledge that the graphics and physics are running on separate threads. The graphics is usually expected to run as fast as possible, while the physics is expected to get its work done in the allocated time. So the fat graphics bar is usually full, meaning it's just using all the CPU it can. But the fat physics bar should be less than full (preferably less than 80% or so), meaning it has completed it's work on time. If it gets all the way to the right, you will fall out of realtime which is bad. (Yes, we know this has been happening, especially in multiplayer races with lots of people ... we're working on it.)

So that's some more description, but not your fix. One of our private beta testers fixed a similar problem (where the purple histogram 'pulsed' to the right on a consistent basis) by putting in a newer graphics card, oddly enough. His CPU was already plenty powerful (newer quad core), but the struggling video driver seemed to be interrupting the whole machine for some reason!? Hopefully in your case, a newer CPU will solve it. But be aware, we've seen some goofy video driver behavior that interrupts multi-threaded applications.
 
Jeremy Miller said:
Histograms are distributions of frame time. Bars are resource utilization. A full bar is full utilization (okay for graphics, not okay for physics). Green start with a G so that is Graphics, Purple starts with a P so that is for Physics.

Tall spikes mean the frame rate time is consistent around a given time. Obviously, the Physics histogram is inverted.
Click to expand...

Thanks. :)

Is this recorded anywhere, or can I see a log of what it has done ?

And thanks Steve , I didn't remember that from RF1 .
 
Thanks very much for the explanations! :)
Also, is there any performance gain to be had from adding some more RAM, or will that just speed up loading times?
 
Has this been solved, or looked at over the past year or two? I still get this in MP, about three quarters through the race.

I have turned down, off, shadows, blur, hdr, faxx and replay. I have a gtx780ti and 32g ddr3.
 
3/4 through what sort of length race?

What are you getting? The CPU graph increasing/spiking? Stutters? Freezes? Pauses where your car sits still then keeps going, having lost time?

The OP in this thread had a borderline CPU that was causing the game to fall out of realtime occasionally. Disabling replays apparently fixed the issue, which I guess means it reduced the system load enough to allow the CPU to handle the game. So yeah, solved. In 2012.
 
Thx for the reply Lazza

We did a 75 min endurance in the BES Mod and the graphics bar was all the way across with its spikes near the beginning. The physics graph was less than 50% then all of a sudden started pulsing towards 75% with lots of little spikes. I use to think that it came same time as the tire contact patch and that there was a problem when hitting some curbs or going off track.

This time I did a clean race and when I started lapping back markers thats when it started lagging. I can normally kind of reset it with pressing the FPS buttons but it did not work this time.
 
I recently upgraded to Win10 and was hoping that would cure it too. Also my AMD FX8350 is OC'ed to 4.8 and also the GTX card. I had them on default speeds for awhile to see it Oclocking is the problem, but it still happened.
 
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