i have started with helloworld template.
added some menu and started performance tool->allocation.
result: 1.9MB
ok, added instance variable ccsprite initialized with an image 1024x1024
and started performance tool->allocation.
result: 6MB
ok, now added to the schen with [self addChild...]
performance tool->allocation.
result: 11MB
is that normal?
every sprite i'll add as child will double my memory usage?
thanks

I don't see anything you posted above to suggest that, but keep in mind: 1024x1024 is a rather large image.

sob...
1024x1024 were only for test, because i did an app, i thought the total memory allocated was 15MB, allocation tools gave me 30MB....
if you make the same things i did, how many memory allocation tool give you?
thanks

I use cocos2d on my game CloudJumper, and it uses maybe 4 sprite sheets at 1024x1024, as well as a few other image resources, and about 20 preloaded sound files. Memory allocation generally hovers around 16-18mb for me.

.....
could you make this try:
open new helloworld template, add this to init function:
CCSprite bg=[CCSprite spriteWithFile:@"sprite1024x1024.png"];
open allocation tool and see the memory allocated, till now should be 4MB of the image+something (for me 2MB)
now add
[self addChild:bg];
open allocation tool and see the memory allocated, here i get 11MB...
should be fast to try, ca you?
thanks

i have found that cocos2d make 2 malloc: here the stack tree:
stack tree

can i avoid that?

You're looking at the simulator, not the device. What you see here does not [necessarily] apply there.

Both the allocations you indicate are in GL and outside Cocos' control.

so could I have in simulator 2 allocation of 4MB and in device no?
i'm working with device for the first time, so all is new for me.
thanks

correct. Profile the device; the simulator is (near) meaningless.