[Zlib-devel] Proposed code change

[Steve Snyder]

On Saturday 28 October 2006 7:11 pm, Mark Adler wrote:
> On Oct 28, 2006, at 7:04 AM, Steve Snyder wrote:
> > While profiling the display of large PNG graphics in Firefox recently
>
> I'd like to add these large PNG graphics to my suite for performance
> testing.  If they're available, please let me know where I can fetch
> them from.  Thanks.

Look here for large PNG files:  
http://ftp.arl.mil/ftp/historic-computers/png/

I'm particularly fond of cyber173.png (12MB), cyber7600.png (11MB) and the 
behemoth pdp11,70.png (20MB !).

If your interest goes beyond sheer size, check out  
http://www.libpng.org/pub/png/ for some fancier (progressive, layered, 
alpha-blended, etc.) graphics.

> > The patch below improves the
> > performance of data output from inflate_fast().
>
> Thank you for the patch.  I will experiment with it.  I now have both
> PowerPC and Intel Macs so I can do some comparisons.

Thanks.  I'll be interested in seeing some non-x86 numbers.

> > The impact of this patch in my observation is that execution time for
> > inflate_fast() is typically reduced by %5.
>
> 5% (if that is what you meant) is not much of a gain.  However it is
> just enough that the patch is worth considering.  Of course,
> modifying the core inflate code must be done with great care.

Yes, I meant a 5% reduction in inflate_fast() execution time.  Not an 
earth-shaking improvement, but I suspect there aren't many dramatic 
improvements remaining in a mature product like Zlib, at least not while 
maintaining its platform-independent nature.