[Gimp-developer] Re: Re: optional scaling in the save dialog…

Hi,
gwidion@??? (2005-02-20 at 0203.45 -0200):
> Let X bre a Huge Amount of Memory (tm) taken by said image, and Y be A
> Couple Kilobytes (tm) used by scaled down version
> Your proccess:
> - Initially using X memory
> duplicate image -> now using x * 2 memory.

I assume there is Copy On Write, thus delaying real memory usage (and
the bandwidth too) until the data changes. Lets see COW at work:

Just after launching gimp:

total used free shared buffers cached
Mem: 514308 444404 69904 0 6180 137996
-/+ buffers/cache: 300228 214080
Swap: 264144 63140 201004

2000*2000 image created and plasma filter run:

total used free shared buffers cached
Mem: 514308 500864 13444 0 6336 138012
-/+ buffers/cache: 356516 157792
Swap: 264144 63140 201004

script-fu console launched:

total used free shared buffers cached
Mem: 514308 503428 10880 0 6372 138268
-/+ buffers/cache: 358788 155520
Swap: 264144 63140 201004

gimp-image-duplicate invoked once, id reported is 2:

total used free shared buffers cached
Mem: 514308 503000 11308 0 6532 138260
-/+ buffers/cache: 358208 156100
Swap: 264144 63140 201004

Invoked 3 more times (ids 3, 4 and 5), to check the apps is not
reusing memory it already owns:

total used free shared buffers cached
Mem: 514308 503008 11300 0 6568 138260
-/+ buffers/cache: 358180 156128
Swap: 264144 63140 201004

OK, pushing the limits, so invoked 46 times more (ids 6 to 51):

total used free shared buffers cached
Mem: 514308 504308 10000 0 7284 136336
-/+ buffers/cache: 360688 153620
Swap: 264144 63364 200780

Used swap and mem (after removing buffers and cache) numbers seem
pretty stable, just mimimal increases in both, some KB reduction
sometimes (other app releasing mem probably). By your rule, the
machine should be crawling now due the 50 copies. Just the pixels are
50 * 2000 * 2000 * 3 = 600 * 10^6, more than the physical RAM.

(__)
(oo) Moo Super Powers
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GSR