Re: [PATCH] diff-delta: bound hash list length to avoid O(m*n) behavior

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On Fri, 3 Mar 2006, Junio C Hamano wrote:
> 
> 	The first round.  The set of objects packed were from
> today's Linus tip (everything down to epoch v2.6.12-rc2), 193309
> objects in total, on my Duron 750 with slow disks.
> 
> 	real		user		sys		bytes		savings
> master	11m17.121s	10m23.280s	0m47.290s       109045599	N/A
> nico	25m37.058s	23m0.770s       2m20.460s	104401392	4.25%
> jc	24m12.072s	21m45.120s	2m16.400s	104409761	4.25%

Ouch.

Btw, it's often worth using /usr/bin/time instead of the bash built-in 
time. Why? Because /usr/bin/time reports one absolutely _hugely_ important 
number (maybe more important than almost any of the other numbers in 
there).

Which one? It's the "minor pagefaults". That's a very good approximation 
of memory usage overhead. 

We've already had one person report that they ran out of memory when 
packing. So memory usage is actually a problem.

Anyway, it looks like the 16-byte window is the way to go, even regardless 
of any memory use issue.

		Linus
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