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Re: freeing srcprops ?
Re: freeing srcprops ?
Tue, 30 Jan 2007 00:31:32 +0100
Thunderbird 188.8.131.52 (X11/20061219)
Neil Jerram escreveu:
>>>>> why use a separate storage pool for srcprop objects?
>>>> At a guess, is it because that they're likely to never need freeing,
>>>> hence can be laid down in big blocks.
>>> I'd guess because setting up a srcprops is critical to start-up
>>> performance, and a double cell doesn't have enough slots to store all
>>> the common properties (filename, pos, copy) directly (as your change
>>> makes clear).
>> All this guessing ... I suspect it was done just because of poor design
>> and/or premature optimization.
> Except you haven't given any objective reasons for why the design is
> poor or the optimization premature.
Any deviation from the standard memory allocation scheme should have a
good reason, or -at least- a documented reason.
This design predates several revisions of the garbage collector, so I
suspect that whatever reason there was for this idea, is no longer
>> on the factual side:
>> 1. the GUILE ends up with 1506 srcprops objects.
> Out of interest, in what scenario?
Startup (with --debug), which you brought up earlier. As I indicated
in an earlier message, I did not see any measurable change in startup
>> 2. this is neglible compared to the 431777 total cells that
>> are allocated.
> (Which suggests to me that the decrease in memory from your change
> wasn't that worthwhile.)
That was not the point of the change.
>> I actually think it would be a good idea to generalize from double cells,
>> to cells containing any number between 3 and 8 SCM values. This would
>> be a better fit with some datatypes, and obviates the procustes
>> hacking to fit all the information inside some struct.
> Maybe. I think this would have to be motivated by looking at
> particular cases where we get benefits from moving struct data into a
> multiple cell. I don't think the srcprops case is clearcut
> (obviously), and I don't see anything wrong with the general approach
> of indirecting to a struct.
I don't mind either, but since the old code was using a struct with
its own 'optimized' memory management scheme, I assumed that an even
better scheme (due to lower memory use) could not be questioned.
>> Because the code made me cringe. It's pointless to have specialized storage
>> for srcprops. it only makes the code more obtuse.
> I disagree. I believe
Can we have some measurable data?
Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen
Re: freeing srcprops ?, Kevin Ryde, 2007/01/18
Re: freeing srcprops ?, Mikael Djurfeldt, 2007/01/30
Re: freeing srcprops ?, Han-Wen Nienhuys, 2007/01/30
- Re: freeing srcprops ?, (continued)