Re: [Ngspice-devel] Possible Low-Hanging Optimizations

[Ryan F. <rya...@up...>]

Hi Dietmar,
I used the CPU profiler in Google's gperftools available here:
http://code.google.com/p/gperftools/ (Documentation here:
http://gperftools.googlecode.com/svn/trunk/doc/cpuprofile.html)

One thing that they don't mention in the documentation is that for
statically-linked binaries, you have to explicitly call ProfilerStart() and
ProfilerStop(). I just called ProfilerStart() at the beginning of main()
and let atexit() take care of ProfilerStop().

By the way, I tried to remove the -static flag, and got a whole bunch of
unresolved symbols when building. Is there some reason that ngspice has to
be statically linked?


On Sat, Feb 9, 2013 at 3:49 AM, Dietmar Warning <die...@ar...>wrote:

>  Hello Ryan,
>
> thanks for you valuable hints. We will take care for it.
>
> BTW - which tool you are using for profiling?
>
> Kind Regards,
> Dietmar
>
> Am 09.02.2013 00:05, schrieb Ryan Fox:
>
> Hey guys,
> I've been doing a little profiling, and a few things have stuck out to me:
>
>  1) About 20% of the time in a transient analysis seems to be spent
> calling seconds(). (It's usually used as IFseconds() by the frontend.) This
> seems to be used for some accounting. It might be useful to be able to
> compile these out if the accounting information isn't needed. (Or perhaps I
> don't understand what this is for...) Most of the time in seconds() is
> actually due to getrusage(), so the easiest way to fix this would probably
> be to just ifdef that call out and return 0 or -1.
>
>  2) check_autostop() accounts for about 5% of the run time, since it has
> to go through cp_getvar(), which appears to be expensive. Could this
> autostop variable be retrieved at the beginning of the job?
>
>  3) In some cases, I've seen checkseed() (which also goes through
> cp_getvar()) take about 10% of the run time. Could it also be retrieved
> once at the beginning?
>
>  I'm not 100% sure of what the implications of these changes would be, so
> I thought I'd run it by you guys to see what you think.
>
>  Thanks.
>
>
>
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