Re: GUILE 2/3 and string encoding cost

[David Kastrup]

Han-Wen Nienhuys <address@hidden> writes:

> On Wed, Jan 22, 2020 at 10:53 PM Han-Wen Nienhuys <address@hidden> wrote:
>
>>
>>
>> On Wed, Jan 22, 2020 at 12:01 PM David Kastrup <address@hidden> wrote:
>>
>>>
>>> > So, what hard data do we have on GUILE 2/3 slowness, and what does
>>> > that data say?
>>>
>>> That data says "humongous slowdown".  There is not much more than
>>> speculation what this is caused by as far as I know.
>>>
>>
>> I can see the 2x slowdown, and it looks uniformly distributed over the
>> whole process. The GUILE 2.0 release
>>
>
> Actually, the I was comparing the -O2 build with the -O0 build.
>
> When recompiling, the Scheme init (reading .scm files) takes 0.31s in 1.8
> vs. 2.7s in 2.0, a 9x slowdown.

The Guile-2 compiler is doing a lot of optimisations, and LilyPond's
startup code switches off byte compilation because the dependencies are
hard to get under control.  The current codebase at least manages to
avoid to compile code with as-yet undefined macros, something that
Guile-1.8 had no problems with but Guile-2.0 refuses.

So the Scheme loading speed is sort-of expected due to Guile relying on
byte compilation for speed and we switch it off.

-- 
David Kastrup