netdev - Re: PROBLEM: Linux kernel 2.6.31 IPv4 TCP fails to open huge amount of outgoing connections (unable to bind ... )

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Message-Id: <20100420.190414.252166338.davem@davemloft.net>
Date:	Tue, 20 Apr 2010 19:04:14 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	zbr@...emap.net
Cc:	eric.dumazet@...il.com, greearb@...delatech.com,
	gasparch@...il.com, netdev@...r.kernel.org
Subject: Re: PROBLEM: Linux kernel 2.6.31 IPv4 TCP fails to open huge
 amount of outgoing connections (unable to bind ... )

From: Evgeniy Polyakov <zbr@...emap.net>
Date: Wed, 21 Apr 2010 04:30:22 +0400

> To return back to exponential bind() times you need to revert the whole
> original patch including magic 5 number, not only bsockets.

Indeed, if we keep that '5' thing there it's just going to still fail
similarly.

> But actual problem is not in this digit, but in a deeper logic.
> Previously we scanned the whole table, now we have 5 attempts to
> find out at least one bucket (without conflict) we will insert
> new socket into. Apparently for large number of addresses it is possible
> that all 5 times we will randomly select those buckets which conflicts.
> As dumb solution we can increase 'attempt' number to infinite one, or
> fallback to whole-table-search after several random attempts, which is a
> bit more clever I think.

If random number generator is not too terrible, just using infinite
limit would be roughly equivalent.
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