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

To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [lvs-users] Kernel 2.6.35 and 100% S.I. CPU Time
Cc: Julian Anastasov <ja@xxxxxx>
From: John Sullivan <jslvs@xxxxxxxxxxxxxxxxxxxx>
Date: Mon, 27 Sep 2010 16:21:27 +0100
Julian Anastasov <ja@xxxxxx> wrote:
> Appended is a patch that drops traffic
> to local addresses. Let me know if it changes something in
> backup server.

I backed out my patch and tried this instead.

It does appear to fix the 100% SI problem, but creates a new
one. Under my test load (fire 100 simultaneous HTTPS requests using
wget at the load-balanced address), all the wgets hang, and netstat
on the backup server shows all 100 connections in this state:

Proto Recv-Q Send-Q Local Address Foreign Address State       PID/Program name  
tcp      113      0 lb-addr:443   ext-host:49914  ESTABLISHED -         

It looks to me like packets on those connections are now just being
discarded (even when they shouldn't be).

I also noticed that ipvsadm starts reporting the weight of the backup
as 0 so it now looks like (on both servers):

  -> localhost:0                  Local   1      0          0
  -> master:0                     Route   0      0          0
  -> backup:0                     Local   0      0          0

(The localhost entry seems to appear whenever there are no available
hosts - I assume this is normal.)

Removing the administrative block on the master allows its weight to
return to 250 (as reported by ipvsadm on both hosts, and the localhost
entries disappear from ipvsadm, and requests can be successfully
served by the master), but the backup never recovers and remains at 0


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