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Where is my bottleneck?
#1
Question 
Hello all,

I have been toying around with PCSX2 lately. Here are my specs:

AMD Phenom II X2 550 (3.1 GHz stock)
ATI Radeon HD 5770 1GB
2GB DDR3 1333

I was trying out God of War (I don't have many games so I can't do extensive tests) on both 0.9.6 and beta 1888, and since the framerate was not to my liking, I decided to OC my CPU. It readily OC'd to 3.7 GHz, roughly a 20% boost on CPU speed alone.

As I have a recent and fairly capable GPU, I was under the impression that the emulator was CPU-bound on my machine, and that I would be getting a linear increase in framerate with the overclock. I turned off all speedhacks and tested my theory at a spot where I got 40 FPS at stock speed. With the OC on, I got 41 FPS, a whopping 2.5% increase. So clearly the bottleneck is somewhere else.

It should not be the GPU, and in fact changing the internal D3D resolution to native has very little impact on the framerate. So what else? My RAM??

Thanks for your help!
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#2
Hmm strange, your test reveals a GPU bottleneck indeed but are you sure the OC was stable? In many cases if the processor isn't getting enough volts for a certain overclock, it might work but way slower than normal.
Also are you using DX9 hardware or DX10 hardware with GSdx? The game will work pretty slowly with DX9 so that could be your problem.
Also post your PCSX2 settings and plugin settings. Normally as you said, the game should be CPU bound as the 5770 is more than enough.
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#3
As you can see in my sig I got very similar rig as yours. Stock clock in phenom II 550 black edition is enough to play most demanding games like Gran Turismo 4 full speed with only little slow downs at few tracks. Radeon 4770 which is bit slower than yours 5770 seems to be overkill for pcsx2. So the difference is ram - 4GB of mine to 2GB yours and maybe unstable, too weak psu in your case (hope not).
AMD Phenom II 550 Black Edition @3.8GHz
4GB DDR2 1066MHz CL5-5-5-15
ASUS Radeon EAH4770 Formula 512MB DDR5
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#4
(03-09-2010, 01:46 PM)Bositman Wrote: Hmm strange, your test reveals a GPU bottleneck indeed but are you sure the OC was stable? In many cases if the processor isn't getting enough volts for a certain overclock, it might work but way slower than normal.
Also are you using DX9 hardware or DX10 hardware with GSdx? The game will work pretty slowly with DX9 so that could be your problem.
Also post your PCSX2 settings and plugin settings. Normally as you said, the game should be CPU bound as the 5770 is more than enough.

Thanks for the quick reply! I admit that I did not run extensive stress tests on my machine after finding the "sweet spot" of 3.7 GHz. I'll try to run a standard CPU benchmark tonight at 3.1 GHz and 3.7 GHz and see if the results match what I get with PCSX2.

I am using DX10 hardware with GSdx 0.15. I was doing my overclocking in AMD Overdrive, and at first I thought that somehow the higher clock settings were 'sandboxed' to the AMD OD application (although this obviously makes very little sense), but CPU-Z reports both cores running at 3.7 GHz.

I am not at home now so I can't give exact settings, but roughly, all CPU enhancements are enabled, all speedhacks are disabled, GSdx renders at 1600 x 1600 using the internal D3D resolution, wait for vertical refresh is on, and frame limiting is set to 60Hz.

I did notice that the cores were nowhere near fully utilized by the emulator: Core0 was roughly at 60-65% and Core1, at 70-75%. However, these figures remained the same with the cranked up CPU clock, so this is not related to the main issue. Still, is it normal to have so much idle time?

Anyway, I'll try to give it a better go tonight with different graphics plugins.

Thanks a lot!
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#5
(03-09-2010, 02:01 PM)midlothian Wrote: As you can see in my sig I got very similar rig as yours. Stock clock in phenom II 550 black edition is enough to play most demanding games like Gran Turismo 4 full speed with only little slow downs at few tracks. Radeon 4770 which is bit slower than yours 5770 seems to be overkill for pcsx2. So the difference is ram - 4GB of mine to 2GB yours and maybe unstable, too weak psu in your case (hope not).

Thanks for your reply! Interesting to see we have similarly specced rigs. Did you try to play God of War on your machine?

I would be surprised if the amount of RAM made such a difference, but who knows... I guess that 2GB is a bit on the low side anyway, but I was more thinking about putting my money on a CPU cooler now that I toying with overclocking.

My PSU is an Arctic Cooling Fusion 550R; I am no expert, but I guess this should be enough as the 5770 is supposed to be less power-hungry than the previous generation, and I don't run into problems when running PC games. Is there an app or something to measure the power load on the PSU?

Cheers!
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#6
No, ram has absolutely 0 impact on PCSX2 speed,size,speed or timings make no difference.

Quote:I am using DX10 hardware with GSdx 0.15. I was doing my overclocking in AMD Overdrive, and at first I thought that somehow the higher clock settings were 'sandboxed' to the AMD OD application (although this obviously makes very little sense), but CPU-Z reports both cores running at 3.7 GHz.

GSdx 0.1.15 or 0.1.5? If it's the first I presume it's the one from the December 30 beta plugin pack?

Quote:all CPU enhancements are enabled, all speedhacks are disabled, GSdx renders at 1600 x 1600 using the internal D3D resolution, wait for vertical refresh is on, and frame limiting is set to 60Hz.
Disable wait for vsync. A great speed hack for God of War (which doesn't break anything in the game afaik) is the mVU flag hack. That should skyrocket your fps Wink

Quote:I did notice that the cores were nowhere near fully utilized by the emulator: Core0 was roughly at 60-65% and Core1, at 70-75%
Totally normal, due to the nature of threaded applications, it is practically impossible to achieve 100% CPU usage or even close to that.

Quote:My PSU is an Arctic Cooling Fusion 550R; I am no expert, but I guess this should be enough as the 5770 is supposed to be less power-hungry than the previous generation, and I don't run into problems when running PC games. Is there an app or something to measure the power load on the PSU?
Nope, no application exists for that...is that 550W? It should be enough given you don't have too many fans and HDDs on
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#7
(03-09-2010, 02:58 PM)Bositman Wrote: No, ram has absolutely 0 impact on PCSX2 speed,size,speed or timings make no difference.
That's what I thought; so this can be crossed off the list.

(03-09-2010, 02:58 PM)Bositman Wrote: GSdx 0.1.15 or 0.1.5? If it's the first I presume it's the one from the December 30 beta plugin pack?
Yes, it's 0.1.15 from the beta plugin pack.

(03-09-2010, 02:58 PM)Bositman Wrote: Disable wait for vsync. A great speed hack for God of War (which doesn't break anything in the game afaik) is the mVU flag hack. That should skyrocket your fps Wink
I'm not sure about the vsync; I get really annoyed by the tearing when it's off. And regarding the mVU flag hack, I do turn it on when I play, it's a great boost indeed (although not enough to truly enjoy the game...) but for now I'm really trying to figure out why OCing my CPU has no impact on the framerate, so it's better left off for these tests I think.

(03-09-2010, 02:58 PM)Bositman Wrote: Totally normal, due to the nature of threaded applications, it is practically impossible to achieve 100% CPU usage or even close to that.
Thanks for the clarification Smile

(03-09-2010, 02:58 PM)Bositman Wrote: Nope, no application exists for that...is that 550W? It should be enough given you don't have too many fans and HDDs on
Yes, it's 550W. I have only one HD, one BD drive, the stock CPU cooler and an extra fan in the case.

Thanks for the advice!
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#8
Well then try another test to take the GPU totally out of the equation:
Set GSdx to DX10 software renderer and compare FPS before and after OC Wink

Yeah with that hardware that 550W PSU will have no problem
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#9
(03-09-2010, 03:39 PM)Bositman Wrote: Well then try another test to take the GPU totally out of the equation:
Set GSdx to DX10 software renderer and compare FPS before and after OC Wink
That's a good idea, I'll do this along with other synthetic CPU benchmarks tonight.

As a side note, are you aware of any homebrew PS2 benchmark or performance tuning application designed to be run on PCSX2 and give various sytem info or debug details that could be useful in my case?

Thanks!
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#10
Nope, nothing like that exists
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