Re: Leopard performance penalty (3x slower), NSPopAutoreleasePool

FROM : j o a r
DATE : Sat Nov 17 20:12:27 2007

On Nov 17, 2007, at 10:53 AM, Gerd Knops wrote:

> I have a complex Cocoa application, 10.4 SDK (no GC etc). Loading a 
> document (and performing a large number of calculations triggered by 
> that) takes 4 seconds under Tiger.
>
> Under Leopard, loading the same document takes 8 seconds until it 
> displays, after which the application is unresponsive for another 4 
> seconds, the entire time being spent in NSPopAutoreleasePool.
>
> I presume that performance penalty is largely due to Leopards more 
> complex memory handling. Has anybody else observed this, and knows 
> of any strategies to minimize that overhead?



What "more complex memory handling" are you referring to? Do you 
compare loading the document between Tiger and Leopard on the same 
machine (same hardware and amount of RAM)?

You should probably investigate trying to create fewer temporary 
objects, and fewer autoreleased objects, as a way to fix this problem 
on your end.

You may also want to file a performance regression bug report with 
Apple. I would suggest including: Shark Time Profile, Shark Time 
Profile (All Thread States), System Profile, top output. Make sure to 
sample the whole duration of loading the document, and include reports 
from both Tiger and Leopard.

j o a r