bug#64735: 29.0.92; find invocations are ~15x slower because of ignores

[Dmitry Gutov]

On 26/07/2023 05:28, Eli Zaretskii wrote:
> > Date: Wed, 26 Jul 2023 04:56:20 +0300
> > Cc:luangruo@yahoo.com,sbaugh@janestreet.com,yantar92@posteo.net,
> >   64735@debbugs.gnu.org
> > From: Dmitry Gutov<dmitry@gutov.dev>
> >
> > Your other idea (spending time in text conversion) also sounds
> > plausible, but I don't know whether this much overhead can be explained
> > by it. And don't we have to convert any process's output to our internal
> > encoding anyway, on any platform?
> We do, but you-all probably run your tests on a system where the
> external encoding is UTF-8, right?  That is much faster.

I do. I suppose that transcoding can/uses the short-circuit approach, 
avoiding extra copying when the memory representations match.

It should be possible to measure the encoding's overhead by checking how 
big the output is, testing our code on a smaller string, and 
multiplying. Or, more roughly, by piping it to "iconv -f Windows-1251 -t 
UTF-8" and measuring how long it will take to finish (if our encoding 
takes longer, that could point to an optimization opportunity as well).