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To: Terry Lambert <terry@lambert.org>
cc: proff@suburbia.net, hackers@FreeBSD.ORG
Subject: Re: SLAB stuff, and applications to current net code (fwd) 
In-reply-to: Your message of "Sun, 26 Jan 1997 14:05:45 MST."
             <199701262105.OAA02273@phaeton.artisoft.com> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Sun, 26 Jan 1997 14:25:45 -0800
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>Vahalia cites a paper:
>	"Efficient Kernel Memory Allocation on Shared Memory
>	 Multiprocessors"
>	McKenney, P.E. and Slingwine, J.
>	Proceedings of USENIX, Winter, 1993
>
>Which shows the sequent code to be faster than the McKusick-Karels
>algorithm by a factor of three to five on a UP, and a factor of
>one hundred to one thousand on a 25 processor system.

   I haven't read that paper, but I suspect that the numbers are wrong due
to spl* having high overhead back then. Since Bruce's "fast interrupt" code,
spl* is almost free, and this changes things greatly. The situation might
change slightly in MP systems, but the total time inside of malloc is so small
that I really doubt that synchronization/serialization will ever be a
significant problem.

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project