[lvs-users] Slow LVS NAT with Debian Squeeze 6.0.3 kernel >2.6.32-38

To: <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: [lvs-users] Slow LVS NAT with Debian Squeeze 6.0.3 kernel >2.6.32-38
From: ROHAUT Sébastien (EXT GFI) <ext.gfi.sebastien.rohaut@xxxxxxx>
Date: Fri, 2 Dec 2011 13:50:15 +0100


I'm encountering a real problem with lastest Debian squeeze kernel.


With 2.6.32-31 kernel (Debian Squeeze 6.0.2) all is working OK.


When upgrading to Debian 6.0.3, LVS NAT started to be very slow. A single html 
page, 4KB, takes about 10-15 seconds to display (immediate on 2.6.32-31).

We tried with 2.6.32-38 and lastest 2.6.32-39, we have the problem with both. 
We tried to upgrade only the kernel from 6.0.2, so we are sure this is related 
to the kernel.


If we access the real server directly, there's no problem, and his IP Gateway 
is on the load balancer, so the IP forwardind seems to work correctly on the 
server. We tried with keepalived 1.1.20 and 1.2.2, It seems it's not related to 
keepalived. So, It must be NAT from IPVS layer.


The only modified kernel values are ipv6 disabling (tried with and without, 
same problem), and ipv4 forwarding.


We recompiled ipvsadm-1.26 (1.25 by default on Debian), and recompiled 
keepalived 1.2.2 on the platform with correct kernel headers, rebooted, same 


Has someone the same problem?


Sebastien ROHAUT


Message initially posted on keepalived-devel list.


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