netdev - Re: [PATCH 0/8 net-next-2.6] udp: optimisations

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Date:	Mon, 09 Nov 2009 06:37:24 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org, lgrijincu@...acom.com, opurdila@...acom.com
Subject: Re: [PATCH 0/8 net-next-2.6] udp: optimisations

David Miller a écrit :

> 
> Looks great, all applied, thanks Eric.

Thanks David, I'll make the remaining patches too.

> 
> I would even go so far as to say that the cutoff to the second hash
> table should be even lower than 10, like maybe 4 or 5.

Probably, but we want to avoid the secondary way if possible,
as this path might have to traverse two different chains.

(total of three cache line accesses to only take a look at chains head/count)

Maybe we can change the heuristic to take into account this like that :

if (hslot->count > 4) {
	...
	if (hslot->count < hslot2->count * 2)
		goto begin_primary_hash_lookup;

This is tuning, and needs benchmarking.

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