[gdal-dev] Changing default value for GDAL_CACHEMAX ? (was Re: Slow warping)

[Ari Jolma]

28.11.2015, 17:13, Even Rouault kirjoitti:
> Le vendredi 27 novembre 2015 13:43:34, Ari Jolma a écrit :
>> 27.11.2015, 14:10, Even Rouault kirjoitti:
>>> Try setting GDAL_CACHEMAX to 150 (6048 * 4032 * 3 = 73 MB. and a x 2
>>> security margin)
>> This reduces the time into 4 s.
>>
>> Quite a bit reduction from several hours.
>>
>> Maybe the default is too low? 150 MB does not seem much.
> Setting the default is not obvious because it depends on use cases and
> hardware configurations. What if people run 100 gdal_translate in parallel ?
> (not very common use cases admidetely, and people can still override the
> default)
>
> Perhaps rather than a fixed value, a percentage of the total RAM would be more
> appropriate (*). Let's say 5% ?
> 2 GB (which is the max for a 32 bit process) -> 100 MB
> 4 GB -> 200 MB
> 16 GB -> 800 MB.
>
> We could also accept a GDAL_CACHEMAX=X% syntax

I that possible? The amount of memory available to a program seems a 
fuzzy topic.

Ari

>
> Even
>
> (*) the ECW SDK does that for its own purposes, with a 25% default AFAIR
>