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

[Daniel Lezcano]

On 08/10/2011 05:54 PM, Daniel Lezcano wrote:
> 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 ?

Oh, and another question. AFAIK, the bridge mode is available since the
2.6.33 kernel.
If we try to enable the bridge mode on a macvlan while this is not
supported, no error is reported.
So I don't know if the RH kernel did backport the bridge mode in their
.32 kernel.