Re: MPS: User GC customizations

["Gerd Möllmann" <gerd.moellmann@gmail.com>]

Ihor Radchenko <yantar92@posteo.net> writes:

> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>
>> Hi Ihor. Soemthing completely unrelated, but I think it might be
>> interesting to play with if you are running an igc Emacs more often:
>>
>>   igc-step-interval is a variable defined in ‘C source code’.
>>
>>   Its value is 0.1
>>
>>   How much time is MPS allowed to spend in GC when Emacs is idle.
>>   The value is in seconds, and should be a non-negative number.  It can
>>   be either an integer or a float.  The default value is 0 which means .
>>   don’t do something when idle.  Negative values and values that are not numbers
>>   are handled as if they were the default value.
>>
>> It's for interactive use.
>
> IMHO, this variable makes little sense in isolation. It only makes sense
> to postpone GCs when we also have the means to increase the thresholds
> when to trigger them. Most of the time, GCs are triggered by
> memory-intensive commands. Extra GC on idle would not help those.

Define GC, so to speak, and define what triggering the GC means in a
concurrent, incremental GC :-)

What this variable does is give MPS notice that the client is currently
idle and it might be a good time to do some work.

> For example, my recent measurement of building agendas displayed 30% of
> the time spend in GC. (whatever this means in the context of our handling
> of SIGPRF)

Exactly, whqt does it mean? And if we don't know, why is it an example
for anything?