netdev - Re: Extensible hashing and RCU

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Date:	19 Feb 2007 23:10:09 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
Cc:	Eric Dumazet <dada1@...mosbay.com>, akepner@....com,
	linux@...izon.com, davem@...emloft.net, netdev@...r.kernel.org,
	bcrl@...ck.org
Subject: Re: Extensible hashing and RCU

Evgeniy Polyakov <johnpol@....mipt.ru> writes:
> 
> My experiment shows almost 400 nsecs without _any_ locks - they are
> removed completely - it is pure hash selection/list traverse time.

Are you sure you're not measuring TLB misses too? In user space
you likely use 4K pages. The kernel would use 2MB pages.
I would suggest putting the tables into hugetlbfs allocated memory
in your test program.

-Andei
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