[Lxc-users] [MySQL] Weird performances problem between containers on a same host

[Daniel Lezcano]

On 08/10/2011 04:51 PM, Mauras Olivier wrote:
> Hello,
> 
> I have several containers running on a host - ~10
> One of them is running a MySQL database. Several of the others are running
> php code under apache that fetch datas from the database.
> 
> Host is using eth0, while my containers are on a bridge using eth1, and
> configured in macvlan bridge mode. Host runs SL6 with 2.6.32 RH kernel -
> Host is a VMWare ESX virtual machine for that matter.
> Ping latency between containers is at an average of 0.050 ms
> 
> What i noted, is that one webapp were getting very slow... After
> investigating, the only thing that i could find, is that requests from
> containers are _slower_ than from any other hosts.
> 
> See below:
> 
> container1 ~ # time (echo "select * from testsuites;" | mysql -h
> container_mysql -u nmp -pxxx testlink)
> id      details
> 42
> (... cut only 25 entries anyway)
> 
> real    *0m0.875s*
> 
> Time varies between 0.8 and 1.2s
> 
>>From the host or another VM on the same network with the exact same request:
> 
> real    *0m0.022s*
> 
> 
> So that particular app that can loop over 19 requests takes sometimes up to
> 20s to display a page instead of ~0.5s from another host...
> 
> Is there some sysctl/settings to tweak or it's just not relevant to make
> requests between containers on the same host??

Hmm, thanks for the detailed explanation.

Can you check with tcpdump if there are problems with the patch checksums ?
And try to disable the TSO and SGO of eth1 if there are available ?