netdev - Re: [PATCH 0/1] Rosebush, a new hash table

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Message-ID: <Zdrbb1oqX9rB4VCV@gondor.apana.org.au>
Date: Sun, 25 Feb 2024 14:17:19 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Matthew Wilcox <willy@...radead.org>,
	David Laight <David.Laight@...lab.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Graf <tgraf@...g.ch>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
	"rcu@...r.kernel.org" <rcu@...r.kernel.org>
Subject: Re: [PATCH 0/1] Rosebush, a new hash table

On Sun, Feb 25, 2024 at 01:14:39AM -0500, Kent Overstreet wrote:
>
> it's a log curve -

Yes it's O(log N/log log N).

> chain length of 16 means you picked a bad hash
> function.

Or that someone is trying to attack you.  The number 16 is the
cut-off where we decide that someone has discovered our hash
secret and can cause a particular to chain to grow without bound.

At this point rhashtable will force a rehash with a different
secret.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt