DT_GNU_HASH latest patches

Eric Christopher echristo@apple.com
Sat Jul 8 02:45:00 GMT 2006


Jakub Jelinek wrote:
> On Thu, Jul 06, 2006 at 07:53:29PM +0000, djamel anonymous wrote:
>> Hello, i am writing you this time about the first variant.after looking at 
>> the benchmark results i noted that there have been a reduction in the 
>> number of l1 cache misses; a reduction in l1 cache misses means a win of 12 
>> cycles ; the difference between the latency of l2 cache and that of l1 
>> cache 15-3.on the other hand replacing a division by a binary and & is a 
>> win of at least 25 cycles, so it think that avoiding tthe division in the 
>> common case may improve performance.
> 
> I don't think it is the modulo that matters, but the smaller footprint
> of .gnu.hash case in that case.  I have implemented what I think you meant
> and the numbers actually convinced me.
> So here is the new set of patches and new statistics.
> take1 is 2006-06-28 state of things, take2 2006-07-03, take3 2006-07-05
> and take4 what is attached here.
> 

A little more documentation on the new method in the code would be 
helpful though. "Don't change this, you'll break it" is rarely enough :)

-eric



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