netdev - RE: [PATCH net 2/2] rhashtable: remove indirection for grow/shrink decision functions

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CAED3A1@AcuExch.aculab.com>
Date:	Wed, 25 Feb 2015 15:51:10 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Daniel Borkmann' <daniel@...earbox.net>,
	"davem@...emloft.net" <davem@...emloft.net>
CC:	"tgraf@...g.ch" <tgraf@...g.ch>,
	"pablo@...filter.org" <pablo@...filter.org>,
	"johunt@...mai.com" <johunt@...mai.com>,
	"kaber@...sh.net" <kaber@...sh.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH net 2/2] rhashtable: remove indirection for grow/shrink
 decision functions

From: Daniel Borkmann [ 
> On 02/25/2015 04:41 PM, David Laight wrote:
> ...
> > Why not cache the 'number of items before we need to expand' value
> > after each expansion, setting it to 'infinite' when expansion is disabled.
> > Then the above check is a simple comparison.
> > You probably don't even need an atomic_read() - provided something is
> > double checked once the first test determines that an expansion is needed.
> 
> Did you read my cover letter? ;)

I probably didn't infer the relevant references :-)

Actually even if some code wanted other rules, provided they
are based on comparing the 'number of items' to a preset limit
the limit could be set during expansion/contraction.

	David

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