Re: [Patch] BaseTools: Optimize string concatenation

[Leif Lindholm <leif.lindholm@linaro.org>]

On Mon, Dec 10, 2018 at 12:09:23PM +0000, Feng, Bob C wrote:
> For the "customized deepcopy" and "cache for uni file parser" data,
> you can see the AutoGen is not slower. The whole Build Duration is
> longer because Make Duration is longer while Make Duration time
> depends on the external make, compiler and linker. So it's not the
> patch make the build slow down.
> 
> Yes,  it's not faster either. I think that because the Ovmf platform
> is relatively simple.  From the build tool source code point of
> view, the customized deepcopy will take effect if the platform
> enabled multiple SKU or there are many expressions in metadata file
> to be evaluated. And the "cache for uni file parser" needs there are
> many uni files.  The Ovmf platform looks not a good platform to demo
> the effect of this patch.

But surely we should not introduce patches said to improve performance
when the only data we have available shows that they slow things down?

If the performance data is not representative, then it is worthless.

Don't get me wrong - if you say "and for this secret platform I can't
share with you, it improves build performance by X", then I may be OK
with a minor slowdown on the platforms I do have available to test, if
X is not minor.

But if the improvement is only theoretical, and we have no evidence
that it helps real platforms, it should not be committed.

Regards,

Leif