[luatex] runtime performance of lua(la)tex incl. gprof

[Hans Hagen]

On 6/21/2023 1:41 PM, Axel Kittenberger wrote:
> On Wed, Jun 21, 2023 at 12:04 PM Taco Hoekwater <taco at bittext.nl> wrote:
> 
>> Using dummy data doesn’t help I believe, because you then need to check
>> the memory pointer against the dummy pointer instead of against NULL. That
>> should not be helpful.
> 
> 
> Albeit the idea was to be branch less in the function that is a bottleneck,
> you are right, I threw something like this together (buggy, it will crash
> on an unknown symbol) albeit it compiled the test that on the other hand
> did indeed not help at all, even very slightly slower (likely due to
> initialization time of the dummy variables)
I checked the HIGH being array patch and indeed it gains max about 1% on 
the pure text ipsum test; in practice pages are of course not that full 
so i see no real gain on a regular 400 page document. Other 
optimizations probaly make that it's not more, but in a more realistic 
test it's also more likely that there are more cache misses anyway if 
the cache is sort of small).

But even little gain is some gain so I suppose we can patch it indeed.

Hans

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