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Re: Benchmarking kicad compilation on CPUs released 6 years apart


Let me encourage some of y'all to stick with an older machine, or keep it
around for testing... the latest build of KiCAD is noticeably laggy on my
machine, which is not terribly fast (but also not that old).  It makes some
of the bugs I have reported worse, and their fixes have been pushed out to
6.x (for perfectly good reasons).

I am a bit manic, though, as Jon can attest; patience is last on my list of
accessible virtues.

*Drew Van Zandt*

On Tue, Oct 29, 2019 at 10:40 AM Simon Richter <Simon.Richter@xxxxxxxxxx>

> Hi,
> On Mon, Oct 28, 2019 at 10:20:45PM -0700, Andrew Lutsenko wrote:
> > I kinda expected 2x maybe 3x decrease because not all computations scale
> > linearly with number of threads. I was pleasantly surprised by almost 6x
> > decrease in clean build time and 5x in incremental builds.
> FWIW, we have a number of bottlenecks in the build process:
>  - dependency generation of common doesn't start until the version header
>    is generated, which only happens after bitmaps and gal are complete
>  - dependency generation of pcbnew_kiface doesn't start until the python
>    wrapper is generated, which takes ages itself.
>  - the python wrapper is compiled as one of the last things, and the linker
>    must wait for that.
> We could probably shave off another two or three minutes of build time if
> we could make sure that we always make progress on the critical path. The
> dependency generation as a side effect pulls all the sources and headers
> into cache, which reduces the effects of I/O latency a bit during
> compilation, so parallelizing with more than the number of threads you
> actually have is probably counterproductive.
> Numbers with CPU time as percent of real time:
>                 clean   ~15     ~5      tip
> E5-2620v4 (32)  7:04.87 5:18.74 5:16.64 3:40.92
>                 2243%   1854%   1854%   1330%
> T2P9D01 (64)    5:16.37 4:14.04 4:10.26 3:20.97
>                 3360%   2558%   2570%   1546%
>    Simon
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