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RE: a way to read the current cpu load from the shell or via acmdline utility in cygwin?
- From: Igor Pechtchanski <pechtcha at cs dot nyu dot edu>
- To: cygwin at cygwin dot com
- Date: Thu, 25 Jul 2002 11:34:01 -0400 (EDT)
- Subject: RE: a way to read the current cpu load from the shell or via acmdline utility in cygwin?
On Thu, 25 Jul 2002, Tony Arnold wrote:
> > I did a google search on "linux top cpu load". Here's a top
> > from the first match:
> > http://www.groupsys.com/topsrc/top-3.5beta9.tar.gz
> > It took about an hour to make it compile and
> > run under cygwin 1.3.12-2 on Win2k. The patch is attached.
> > Note: I just compiled and ran the code; I haven't verified
> > the correctness of the output. It seemed to work without
> > crashing, and the output looked plausible. I also haven't
> > tested it on any system other than mine (above). Try it at
> > your own risk.
> Thanks for this, it's a good start to getting top working under Cygwin.
> My question is that when you run the Configure script what do give as
> the 'appropriate module' for the machine? I've used 'linux' but I wonder
> if there is a better option, or whether we should invent a Cygwin
> machine definition?
'linux' seemed to work for me. I've had to comment out some
linux-specific stuff, though (see patch:
http://cygwin.com/ml/cygwin/2002-07/msg01974.html ), so creating a cygwin
module might be a better long-term solution.
> Secondly, when it runs, I'm not convinced the figures are correct! For
> example, my setiathome process should show almost 100% cpu utilisation,
> but it shows 0%! Is this a refelction of my choice above, or problems
> with the /proc file system infotmation?
As I said, I haven't verified the correctness of the output. As my
machine is mostly idle, the output looked plausible (compatible with that
of the Win2k Task Manager). Now that I actually ran an experiment with a
CPU-intensive process, it looks like top downscales utilization by a
factor of 3 (again, on my machine and configuration).
> Hints and tips on this much appreciated.
> Regards, Tony.
The way top calculates CPU percentage is by dividing the accumulated
process time since last check by the wallclock time since last check. As
far as I can see, the code itself looks correct. Thus, the blame would
probably lie with either the /proc filesystem entries (particularly
/proc/$PID/stat) or the gettimeofday() implementation/granularity.
I'm sorry I don't have time to investigate further.
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