bottlenecks

[Robert Weber]

--------

> 
> The internal librsync procedure used up only about 1/20th of the CPU
> time as the external rdiff procedure, meaning I suppose that 95% of
> the CPU time was spent forking, setting up the external rdiff process,
> etc.  
> 

I was just able to do some code work on librsync's md4 and crc32 code to
get a reasonable speedup.  Granted, this is only an issue with large files,
but every little bit helps.  I have posted my changes to the developers,
and hopefully they will pass inspection and find their way in to the
library.

The speed up for a 2GB file sig was

(hannah)[4:00am]:/hannah/scratch/medialib > /usr/bin/time ./rdiff.orig
signature /usr/local/pc/C.diskimage foo2

real     3:19.3
user     2:07.0
sys        24.4
(hannah)[4:03am]:/hannah/scratch/medialib > /usr/bin/time ./rdiff signature
/usr/local/pc/C.diskimage foo1                                                   

real     2:47.2
user     1:18.6
sys        23.7

							Robert Weber
							UnixOps
							University of Colorado