Hi!
I’m just wondering whether this is normal: Renoise needs lots of CPU for me while a song is playing. More specifically, it’s especially the pattern editor which does. Even playing simple songs which use just a few VST instruments take up 60% oder even more CPU resources. As soon as I minimize Renoise though, or just bring up the Instrument Envelopes (thus hiding the scrolling Pattern Editor), CPU usage drops dramatically. Anyone else having this problem?
Is it the kind of cpu eating that slowly increases and lowers when you for instance move your mouse etc?
Might it be you have a hyperthreading cpu?
If you have Windows:
Renoise should turn this off automatically for it’s own thread, but you can check it out in the taskmanager and rightclick upon the process, then select “set affinity” (bottom option of context menu) so see if all cores but one are unchecked.
Renoise only works flawlessly on one core.
I don’t know how you could set the CPU affinity on an intel- Mac though.
Might be worth checking your video drivers - make sure hardware acceleration is turned on otherwise graphics related tasks might be straining the CPU while your GPU is sitting idle.
Maybe?
Also - turning off pattern-scroll eases the CPU somewhat I find.
Nope, it’s instantaneous. It also drops immediately as soon as I hide the pattern editor or minimize Renoise. The only possible explanation for me is that the problem is indeed the scrolling of the pattern while the song is playing, as funny as it may sound… 
I have an Athlon XP2800+, which only has one core so that shouldn’t be the problem…
Hardware acceleration is activated of course.
I just tried starting Renoise and then hitting Play without any song being loaded… the CPU usage went up from 1% to ~25% immediately. That’s quite a lot for just scrolling some text… 
It depends, if you set the framerate to make it 250 fps (impossible but just to give you an idea) so you have ultrasmooth scrolling, it may ask such an amount.
Frankly the framerate does not really needs to be higher than 30fps or so.
And hardware accelleration pops more into it’s right in full-screen mode (alt-enter).
The framerate only applies to windowed mode.
I have set the framerate to 30 (was 60 before), and it didn’t make any difference. The Pattern Editor is still sucking CPU like hell… 
In the meantime, I came to the conclusion that the scrolling of the pattern is NOT the problem… because when I disable it, the problem still remains and the pattern editor sucks up lots of CPU time even though the patterns are not even scrolling. Still, as soon as I switch to the Instrument Envelopes or Sample Editor, or minimize Renoise (i.e. do something so the pattern editor is not being displayed), CPU load drops dramatically, sometimes more than 50% even! I’m pretty sure this is a flaw (you could call it bug even) in Renoise and should be looked after. 
I got something similar in the past, though not so dramatic. Updating drivers helped a lot, so make sure you have the latest ones.
which video card do you have, by the way?
Mine is a GEForce4, and the latest drivers improved renoise GUI quite a lot
I have a GeForce4, too… but I updated the drivers just two weeks ago or so. I don’t think that’s the problem though because the pattern editor sucks up CPU time even when nothing at all is happening on screen, i.e. with scrolling disabled. Seems to me as if something CPU heavy is going on in the background as soon as a song is playing with the pattern editor shown.
then the problem could be a specific VST which does not run well in Renoise?
did you recognize any VST which is present in all of your songs?
did you try muting one track at a time to see if there is a specific one which is causing the problem?
you can also check the isntrument properties to see how much CPU an instrument consumes
As I said above, the Pattern Editor also sucks up lots of CPU if I just press play with no song loaded at all. So it doesn’t seem to be a problem with VSTs. Also, if a VST would suck up the CPU time, why would the CPU load drop so dramatically as soon as the Pattern Editor is hidden?
Has Renoise ever run good on your machine, like maybe before you updated your gfx driver two weeks ago?
Have you been fiddling with Renoise cfg files? I’m guessing it may be a font issue?
I have only recently discovered the issue (or let’s say, become really aware of it) because I started working with VST plugins, some of which require quite a lot of CPU (more than samples at least ). So just since then did I recognize that Renoise starts choking even with only some VSTs working and wondered why, as my CPU should have no problem with that. And what I discovered was that the problem are indeed not the VSTs, but Renoise itself. The thing is, I never had an eye on the task manager before that while Renoise was running, so I have no idea since when the problem occurs or whether it even has always occured. I’m sure though that Renoise already had bad performance before I updated the drivers, it is just now that I really investigated what the issue is because it was starting to be really annoying me.
Concerning your second question, no, I have not fiddled with the files. I just freshly installed Renoise yesterday (1.5.2, registered) hoping the problem would vanish (had the same problems with 1.5.1 already).
I’m running Win2k (SP4) btw, perhaps it’s a problem specific to it? 
Further investigation: The higher the BPM (or overall speed), the higher the CPU load. I get around 55% CPU load at 180BPM, Speed 03 (no song loaded, just playing empty patterns). When I raise the speed to 06, the CPU load decreases by half, so it’s directly proportional. Again, disabling pattern scrolling only has a small effect. Hiding the pattern editor causes CPU load to drop to virtually nothing…
Also tried updating DirectX? (It really looks like a graphics glitch of some sort because the processing of playing and time calculation does not stop when you minimise Renoise)
Which version do you run?
Yes, but the strange thing is that the problem persists even if I disable scrolling, so that nothing is really moving on screen…
If you mean DirectX, it’s 9.0c. If you mean Renoise, it’s 1.5.2 (as said above).
I only have one soundcard (AC97 onboard). Disabling it just has the effect that Renoise doesn’t find a DirectSound device, thus I’m not able to press play… d’uh. 
Well AC97 onboard says nuff actually.
But it could share it’s irq with other devices, to find this out go to your start-button thingy and then click “run” enter “msinfo32” in the textfield.
Then go to hardware resources and click “conflicts/sharing”.
See what address or worse:what IRQ your audio interface is sharing.
I’ll just tell you right in the face that onboard devices are not the real thing to use, specially not cheap manufactured devices like the AC97 soundcard. It does well for the ordinary desktop audio, playing some mp3’s and doing some regular gaming, but it’s not a performer.
There may be someone who created a hacked non-original driver for it to boost it’s performance (since it’s a very general soundchip used) but i don’t give high hopes for that.
Other than that sharing IRQ’s and addresses with other devices are pretty funest. specially if they share them with network and serial devices (or your GPU).
I don’t know if you can set your audiocard in Legacy mode in your BIOS, but this also requires you to disable ACPI and assign a specific IRQ to the soundcard in the BIOS or in windows.
But you can only set resources if your BIOS resource handling is set to full legacy mode.
Most boards don’t support this feature anymore.
Maybe, but how does this explain the high CPU load which is present only when the pattern editor is displayed?
I just said, I’m unable to press play when there is no soundcard and thus unable to check it… the CPU load increases only when Renoise is in replay mode.
The CPU load shown in Renoise is audio-only related so even when playing, DirectSound is ordered to retreive and perform an audio stream even though in your case the stream is empty or flatlined.
This however does not explain why it drops as soon as you minimise Renoise or go to the Instrument Envelope area. So that’s why i thought about graphic drivers in the first place.
(or maybe chipset drivers that need an update, i’ve seen a lot of funny causes in a lot of strange corners in my life of PC troubleshooting.)
I was talking about the CPU load displayed in the task manager though, not the one in Renoise, just to make it clear. And I really can’t see how my onboard soundchip or my GPU could be related to the problem, keeping in mind that the problem vanishes as soon as the Pattern Editor is gone, and also that the Pattern Editor (and ONLY the Pattern Editor) eats CPU even if nothing happens on screen…
Or maybe, it is indeed a bug in Renoise?