Re: [lvs-users] Kernel 2.6.35 and 100% S.I. CPU Time

To: JL <lvs@xxxxxxxx>
Subject: Re: [lvs-users] Kernel 2.6.35 and 100% S.I. CPU Time
Cc: lvs-users@xxxxxxxxxxxxxxxxxxxxxx, 楷子狐 <higkoo@xxxxxxx>
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Tue, 14 Sep 2010 00:25:37 +0900
On Mon, Sep 13, 2010 at 03:52:29PM +0100, JL wrote:
> OK, More information:
> I hope someone who is up on ipvs kernel side is listening!

I am listening, sorry for not responding earlier.

> If a backup machines receives an IPVS state update packet (the ones
> sent to with a certain number of connections in it
> (somewhere between two and eight, inclusive, will trigger it) then SI
> goes to 100% on the backup immediately.
> Firewalling insulates you from the problem (although, of
> course, is unsuitable for a live deployment).

Presumably turning off connection synchronisation
has the same effect.

> Feeding in only one connection at a time (slowly enough that the each
> have their own IPVS packet) doesn't trigger the problem.

So it occurs if the number of synchronised connections in
a single packet is between 2 and 8. So 1 is ok, and so is 9?

> This happens with linux, but not

That is a fairly wide number of kernel versions.
But if it is easy to reproduce then it should be fairly easy to track down.

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