Re: Checking system cpu load when forking?

Some things that don't compute:

"cross-platform" AND Win32::API in the same paragraph
but I don't want it to be a big CPU eater. Anybody have a good way to do so reliably?

I'm not even sure as to what your trying to do, Dynamic forking maybe? If so check out Parallel::ForkManager as a starting point, and fork, perlipc, perlfork. Did you even bother looking at Sys::Load's docs. It apears as if it only gets information, which is system specific not task specific. Could you describe how you would like that to help? Or maybe more of what your goal is? Essentially, if a task takes 500,000wallclocks to complete, it doesn't matter how you cut it, it is going to take at least 500_000wallclocks.

Evan Carroll
www.EvanCarroll.com

Comment on Re: Checking system cpu load when forking?

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Re^2: Checking system cpu load when forking? by mattr (Curate) on Nov 09, 2005 at 03:35 UTC
Hi, and thanks for the reply! To clarify.. The objective is that I want my app to work quietly without slowing down the system even if it is being run on slow hardware or on hardware the resources of which are already in high demand i.e. by virus checking, printing, etc. The question is how to tell how busy the machine is, and to do so reliably with a minimum of interaction and a minimum of hassle whether the machine is a windows 98 pc, a linux laptop, a mac, or some windows or linux server. Sys:Load works on linux so I mentioned Win32::API with the idea that I might have to think up some alternate strategy to be used in case we are running on a windows machine. Which I don't want to do. Yes, I've read the Sys::Load docs (a related page also says it is limited to systems with getloadavg() apparently) and it works fine on linux anyway. Haven't tried it anywhere else. I was hoping Sys::Load would help since it returns an average of cpu load for the last minute. This knowledge would let the software take action when it load is above 0.8. It might tell a user that it is not a good idea to add more concurrent jobs, or it might choose to prioritize, delay or offload some things. Wallclock doesn't tell you how hard the machine is working. It is more about useability and figuring out whether more resources should be added. I do have some studying to do, though I have of course read about Parallel::Forkmanager which I plan to use, and POE which I would also like to use in places. I haven't used these modules yet though, and I am not so familiar with perlfork. (The links you provided about perlipc and perlfork are quite nice, I'll go through them, thank you). I hope this is enough information. It would be nice if there was a PP heuristic to figure out how much you are stressing a machine and also to derive a baseline for how much power the machine has so you can plan resource loading in advance. Also I don't want to rewrite a module or require tweaking even when moving between machines. However if necessary I'm willing to consider a collection of two or more platform-specific solutions to figuring out the cpu load (and maybe available bandwidth and disk space too)	[reply]

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Re^2: Checking system cpu load when forking?
by mattr (Curate) on Nov 09, 2005 at 03:35 UTC

The objective is that I want my app to work quietly without slowing down the system even if it is being run on slow hardware or on hardware the resources of which are already in high demand i.e. by virus checking, printing, etc. The question is how to tell how busy the machine is, and to do so reliably with a minimum of interaction and a minimum of hassle whether the machine is a windows 98 pc, a linux laptop, a mac, or some windows or linux server.
Sys:Load works on linux so I mentioned Win32::API with the idea that I might have to think up some alternate strategy to be used in case we are running on a windows machine. Which I don't want to do.
Yes, I've read the Sys::Load docs (a related page also says it is limited to systems with getloadavg() apparently) and it works fine on linux anyway. Haven't tried it anywhere else. I was hoping Sys::Load would help since it returns an average of cpu load for the last minute. This knowledge would let the software take action when it load is above 0.8. It might tell a user that it is not a good idea to add more concurrent jobs, or it might choose to prioritize, delay or offload some things. Wallclock doesn't tell you how hard the machine is working. It is more about useability and figuring out whether more resources should be added.
I do have some studying to do, though I have of course read about Parallel::Forkmanager which I plan to use, and POE which I would also like to use in places. I haven't used these modules yet though, and I am not so familiar with perlfork. (The links you provided about perlipc and perlfork are quite nice, I'll go through them, thank you). I hope this is enough information. It would be nice if there was a PP heuristic to figure out how much you are stressing a machine and also to derive a baseline for how much power the machine has so you can plan resource loading in advance. Also I don't want to rewrite a module or require tweaking even when moving between machines. However if necessary I'm willing to consider a collection of two or more platform-specific solutions to figuring out the cpu load (and maybe available bandwidth and disk space too)

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