netdev - Re: [Patch] Establishing more than 64K outgoing TCP connections

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Message-Id: <20081106.222323.230548519.davem@davemloft.net>
Date:	Thu, 06 Nov 2008 22:23:23 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	yavor@...plifymedia.com
Cc:	netdev@...r.kernel.org
Subject: Re: [Patch] Establishing more than 64K outgoing TCP connections

From: Yavor Goulishev <yavor@...plifymedia.com>
Date: Fri, 7 Nov 2008 01:12:36 -0500

> I see that you want to access the hash table in O(1)  and
> you try to get a port number at empty bucket. This is clever.
> However having hash table size 65536 and hash function just the port number can
> work only for 64K binds, right? If I need more they need to go in the chains.
> 
> So may be having a better hash function and configurable table size (/proc/sys/net/...)
> can work without limitation and with good performance.
> For example:
>     hash_fn = (port + local_ip) % size

All you have to preserve is that the hash distribution is evenly
spread.  That is what your patch violated.  I'm not asking for O(1)
access, I'm asking for O(num_ports_bound / hash_table_size) access.

Trying to solve all other kinds of issues just distracts from the
core issue.
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