[ul1984]

i think 2 weeks ago i started doing some folding, on my Powerbook, it all went well, so i decided to start folding on my parents iMac 800 as well.

and within a day i got complaints from my little brother that it was slower then usually(in games mostly i guess)
i thought running at nice +20 it would make it run at idle priority and not disturb any other processes but i was wrong.

so i tested on my own computer, using Quake 3 timedemo, 164FPS with Folding running at nice +20
and 230FPS or so with folding not running at all.

i remember reading back in the 10.0 days that nice was broken on OSX, but i thought it would have been fixed long since then, but it seems it hasnt.

when i ran linux ppc on my old G3 400Mhz a year or so ago, i reemember using "nicing" big compiles like this "nice make bla bla bla" etc, and it worked so good, couldnt feel it was compiling at all, while scrolling web pages etc.

so then i decided to try that on OSX, i compiled some UNIX software, with at lowest priotity, and the whole computer got a LOT slower, scrolling in safari very jumpy...

i had to write a little simple deamon(if u can call it that, more like a shell script, but writting in C, cus thats all i know) for parents iMac, that will check its load avg, and "killall -STOP" folding@Home, when it gets too high, it does seem to work very well, i have crosschecked my daemons logs with that of "last", and it stops folding@home while ppl are sitting at the computer..

well it really slowes my folding down, cus now it only gets to run about 8 hours a day on that iMac, when they are sleeping..


as i said im REALLY dissapointed in Mac OS X, cant be that hard to fix.....if linux can do it why cant OSX..

btw i think i remember reading a while ago, that macosx had like 127 pritorites and the 40 pritorites that u can access using "nice" was just the "middle" ones of those 127, is that true??

maybe its possible to somehow set folding@home to run at the lowest possible priority, using some MACH tool or function?

[sideus]

I was compiling xchat, two F@H clients running, and using Safari at the same time the other day. No noticeable slow down for me. But it probably depends on available RAM and system speed.

[ul1984]

the thing is, the scheduler isnt working as i was expecting it to do, when i have it set to idle priority i want it to have idle priority.

by idle priority i mean that if i for example run quake 3 and its wants all of my CPU it should get all of my CPU.

as i could see from my FPS tests it didnt work like that, and i did those tests many times in a row, so i dont think it was due to swapping or due to my RAM.

you say you couldnt feel any slowdown, i think thats because you using a dual processor machine(i assume you do), if im running only Folding@home i almost cant feel its running.
but if i start a compile too, it gets a little jumpy, while scrolling(using the scrollbar), if i scroll using my scrollwheel i cant really feel im compiling either, because it scrolls in "jumps" i guess

if you would compile 2 apps at the same time, i think you could feel it too.

i wouldnt really mind that i cant get idle priority myself on my own computer, cus i just stop folding@home, if i really need all my CPU. It sucks not being able to set it to idle priority on someone elses computer, usually if you'd ask someone if you could have it running in the background you'd say that it would only take up spare CPU cyclces, but if that isnt true, then i dont think i will be running it on many computers..

just too bad

[reader50]

'nice' was broken in 10.0 but got fixed later. By setting two equal threads to '+20' and '-20', I can produce quite a spread in CPU usage. (OSX 10.2.8 - G4 350 single processor)

My guess would be that the systems are constrained on free RAM, and you're getting swapfile activity to slow things down.

[Shaktai]

Originally posted by reader50:
My guess would be that the systems are constrained on free RAM, and you're getting swapfile activity to slow things down.

I tend to agree with reader50. How much RAM are you running on each machine?

My iBook 600 tends to see occasional slowdowns with 256mb of RAM. My PowerMac 800 almost never sees any slowdowns with 512mb of RAM unless I start working with large graphics files. The iBook slowdowns are consistently the result of swapfile activity. OS-X handles it all as well or better then my Linux and Windows boxes.

[Scotttheking]

I've also seen this on OSX, and to a lesser extent, on linux. I'll do more poking. Personally, when gaming on my G4 500, I turn fah off.
However, I just checked, and it works great on win2k Absolutely 0 CPU usage on FAH when something else pegged the processor.

If you'd be willing to distribute your script, that'd be very useful. Something that would stop the client when the load hits 1.00, then start it again when it drops down, would be just perfect. Just make sure it sends the kill (and not -9) to the fah client, not the core. I'm pretty sure that's how to stop it. (I'll check)

[ul1984]

'nice' was broken in 10.0 but got fixed later. By setting two equal threads to '+20' and '-20', I can produce quite a spread in CPU usage. (OSX 10.2.8 - G4 350 single processor)

My guess would be that the systems are constrained on free RAM, and you're getting swapfile activity to slow things down.

ive done some more testing now, both under linux and OSX using equal processes, i used "yes > /dev/null":

this is about the avg cpu usage:

OSX:

2 equal processes with with nice +20
"nice -n +20 yes > /dev/null" 40% usage
"yes > /dev/null" 60% usage

3 equal processes, one with nice +20
"nice -n +20 yes > /dev/null" 20% usage
"yes > /dev/null" 40% usage
"yes > /dev/null" 40% usage

linux:
2 equal processes with with nice +20
"nice -n +20 yes > /dev/null" 15% usage
"yes > /dev/null" 85% usage

3 equal processes, one with nice +20
"nice -n +20 yes > /dev/null" 7.5% usage
"yes > /dev/null" 46.25% usage
"yes > /dev/null" 46.25% usage

this means both OSX and linux dont seem to be able to get idle priortiy on a process with nice +20, but under equal conditions, linux gives the niced process a lot less CPU time.

i think this might be the reason OSX seems to multitask better then windows? cus it will always give processes cpu time, even those with low priority, so that no process will ever stop running. maybe this is a good thing for most applications.

but there should be a way to set a process to absolutly idle priority, like you can do on windows.

I tend to agree with reader50. How much RAM are you running on each machine?

My iBook 600 tends to see occasional slowdowns with 256mb of RAM. My PowerMac 800 almost never sees any slowdowns with 512mb of RAM unless I start working with large graphics files. The iBook slowdowns are consistently the result of swapfile activity. OS-X handles it all as well or better then my Linux and Windows boxes.

512MB RAM on both my box and my parents

I've also seen this on OSX, and to a lesser extent, on linux. I'll do more poking. Personally, when gaming on my G4 500, I turn fah off.
However, I just checked, and it works great on win2k Absolutely 0 CPU usage on FAH when something else pegged the processor.

what you said about a lesser extent on linux, seems to be supported by my tests above.

If you'd be willing to distribute your script, that'd be very useful. Something that would stop the client when the load hits 1.00, then start it again when it drops down, would be just perfect. Just make sure it sends the kill (and not -9) to the fah client, not the core. I'm pretty sure that's how to stop it. (I'll check)

Of course,

accually i dont kill FoldingAtHome at all, i just send it a -STOP signal, which causes it to pause, and then when i want it to continue running i send it a -CONT signal
(i just love STOP/CONT, its so useful, for example to pause all BitTorrent downloads, without having to close BitTorrent)

here it is: FahControl.tgz

feel free to tweak it anyway you want, the way i have it now seems to work best for me