HELP! OpenMPT increases my processingpower!!!!!!! (I think)

Waxhead · July 14, 2007, 16:11:17

This may sound INSANE but when I'm running OpenMPT i experience something rather strange.
I code a bit every now and then and have written a tool who does some processing and sends this information to a 3D viewer. The strange thing is that when OpenMPT runs in the background playing some music both my program and the 3d viewer (who a friend of mine wrote) is running A LOT FASTER!!!!!!

This sounds totally bananas but it's true - honest! - So I would like to ask one of the developers what the heck they did in the code!

PS! I'm running a E6600 Core 2 duo processor with 2gigs of ram with XP SP2. The only thing I can imagine is that this is related to some screenupdate / refresh or something simmilar. Even if I tick off follow song it still speeds up. Any details on what is making OpenMPT a CPU turbocharger would be appreciated

seventhson · July 14, 2007, 16:44:54

Isn't that because dual core is optimized to run multiple programs at the same time?

LPChip · July 14, 2007, 16:49:22

It almost sounds that the guy that programmed the viewer made somekind of bug, or syncing it to an audio buffer or so...

I guess the reason this is happening means that that viewer could be faster if he'd remove this bug.

Waxhead · July 14, 2007, 18:00:20

The viewer is based on OGRE (it's written in pure basic (sigh)) but it works

- My own program (written in C) is also speeding up a bit.... The only thing I can think of is that OpenMPT somehow magically increases the response time of network sockets

Relabsoluness · July 14, 2007, 18:31:24

Quote from: "Waxhead"The strange thing is that when OpenMPT runs in the background playing some music both my program and the 3d viewer (who a friend of mine wrote) is running A LOT FASTER!!!!!!

What an outrageous bug in OpenMPT - this must be fixed

LPChip · July 14, 2007, 19:20:55

Quote from: "Relabsoluness"
Quote from: "Waxhead"The strange thing is that when OpenMPT runs in the background playing some music both my program and the 3d viewer (who a friend of mine wrote) is running A LOT FASTER!!!!!!
What an outrageous bug in OpenMPT - this must be fixed

Hahahaha ROFLMAOBBQ

Waxhead · July 14, 2007, 21:20:34

Ultra-LOL

, hehe perhaps some of the devs can explain what can cause this hehe

Sam_Zen · July 14, 2007, 23:41:08

Some vague considerations :
3D images have to be rendered on the spot and take a lot of processing power and of the video card.
If this has priority in the procedure, then OMPT gets in a kind of waiting queue to get some memory access once in a while.
So maybe OMPT is desperately trying to catch up with things on the screen.

Waxhead · July 15, 2007, 08:34:26

OpenMPT runs fine. No jerkiness whatsoever, also the other apps does not use all available CPU time (nor do they spend much time in kernel time).
So there is a reason that running 3 apps is "faster" than running 2. It must be some kind of signaling who makes my apps go faster. So I would really like to hear from one or two devs what actually happens when OpenMPT starts playing music and scrolling it's window.

SoundCrafter · July 22, 2007, 02:18:57

Quote from: "Seventhson"Isn't that because dual core is optimized to run multiple programs at the same time?

He's right, I believe. I don't think this phenomenon would occur on a single-core proc (Although I'd LOVE to see it on a quad-core!)

I'm not familiar with the E6600. Does that have HT and what's the core speed on it? Is it Core 2 Duo or Extreme?

Waxhead · July 22, 2007, 06:57:18

This has nothing to do with the processor. (especially since I have disabled speedstep and other boring things).

Think of the CPU as a motor (a dual core as two motors). If the applications are load for these motors there is no motor in the world who goes faster with more load.

Two loads balanced over two processors will run faster than the same load on one processor. Three applications runs slower than two no matter what. This are the reason I'm curious about this. It must have something to do with some signaling to the OS. I just want to know what

älskling · July 22, 2007, 07:01:00

It's probably just two wrongs making a right for once.

dBlues · July 23, 2007, 18:32:37

Sounds like the CPU load calculation was faulty. I really cannot think of anything else, except that Microsoft might have a conspiracy with Intel/Duron. They planted in a new "feature" which slows new machines down to sell more powerful processors. MPT is currently breaking this feature. So you better file in a bug report to M$...

Sulik · November 03, 2007, 06:56:59

If your application is limited by the OS scheduling period, it may be due to multimedia timer functions in MPT lowering the scheduling period (and/or generating more events allowing for more fine-grained context-switching).
It's specially likely if your application contains calls to Sleep(1).
You can experiment by calling timeBeginPeriod(1) in your app to see if you get similar results.

Waxhead · November 03, 2007, 11:02:48

Quote from: "Sulik"If your application is limited by the OS scheduling period, it may be due to multimedia timer functions in MPT lowering the scheduling period (and/or generating more events allowing for more fine-grained context-switching).
It's specially likely if your application contains calls to Sleep(1).
You can experiment by calling timeBeginPeriod(1) in your app to see if you get similar results.

I actually do a Sleep(50); in my mainloop and I got another thread waiting for data over the network. But thanks for the tip