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

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Message-ID: <Zdk2YgIoAGOEvcJi@gondor.apana.org.au>
Date: Sat, 24 Feb 2024 08:20:50 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, Thomas Graf <tgraf@...g.ch>,
	netdev@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	maple-tree@...ts.infradead.org, rcu@...r.kernel.org
Subject: Re: [PATCH 0/1] Rosebush, a new hash table

On Thu, Feb 22, 2024 at 08:37:23PM +0000, Matthew Wilcox (Oracle) wrote:
>
> Where I expect rosebush to shine is on dependent cache misses.
> I've assumed an average chain length of 10 for rhashtable in the above
> memory calculations.  That means on average a lookup would take five cache
> misses that can't be speculated.  Rosebush does a linear walk of 4-byte

Normally an rhashtable gets resized when it reaches 75% capacity
so the average chain length should always be one.

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