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Re: bignum branch

From: Eli Zaretskii
Subject: Re: bignum branch
Date: Mon, 16 Jul 2018 21:06:01 +0300

> From: Stefan Monnier <address@hidden>
> Cc: address@hidden
> Date: Mon, 16 Jul 2018 12:09:41 -0400
> > and if the performance is comparable with --with-wide-int.
> Not sure what kind of performance you have in mind: a plain old 32bit
> build with bignums will almost inevitably be more efficient than
> one --with-wide-int when dealing with buffers <512MB, but it will just
> as inevitably be less efficient when dealing with buffers between 512MB
> and 2GB.

Between 512MB and 2GB is what I had in mind.

> > Is it reasonable to expect a comparable performance from native 32-bit
> > code calculating 64-bit values vs function calls?  I think I'd be
> > surprised.
> Operations on (small) bignums will be significantly slower than
> operations of "long long" 64bit integers, yes.  How this will impact the
> overall performance when dealing with buffers between 512MB and 2GB
> I don't know: these already tend to suffer from various other
> performance problems and I don't know if one will dwarf the other or if
> they will make each other more painful.

That's what I'd expect as well, and so I don't think --with-wide-int
will die too quickly.  I personally need to use buffers larger than
0.5GB all the time on my daytime job.

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