Messages in this thread | | | Date | Thu, 19 Mar 1998 23:03:53 +0100 | From | Pavel Machek <> | Subject | Re: Idle time reported by top / 386 compiling kernel |
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Hi!
> I know that I need to upgrade my system, but I now have > a 386DX33 (AMD & copro) and 20 Mbytes of RAM.
No, don't upgrade that beast. Slow machines result in better software, and I do not want to be last one running 386/8Meg.
> I was compilling 2.1.90 yesterday, and I noticed (using top > with a "nice" priority of 19) that even without swapping > or accessing the disk (no disk light or noise!) I have > sometime idle times of 50-70% - "cc1" and other "make" do > not take most of the CPU time available.
Ok, I'll clean my kernel and try it... Sorry, my machine has not enough RAM for this test. I would appredicate if you could reproduce this bug with disk not used at all...
Hmm, yes, it looks like I can see it. But it looks like measurement error. TOP uses idle=100%-sum{times of all processes}. Fix top.
Yes, top is lying badly. I've just seen it telling me 97% idle after period of complete CPU load (according to debuging leds.)
I guess that this happens:
CPU is loaded by process 'A' which exits just at the end of measurement interval.
> Is that in relation with "cc1" deacreasing its priority > to 20 while building the kernel ?
No.
> Is that a well known problem in the sckeduler ?
No.
> Is that a measurement problem (Kernel profiler > Define not set) ?
Kernel profile does not have anything to do with this.
Pavel -- I'm really pavel@atrey.karlin.mff.cuni.cz. Pavel Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).
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