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

[Mauras Olivier]

Ok so to make things working out quickly, i added some network interfaces to
the host and moved the MySQL container on a second bridge using eth2
No more speed problem... It only happens on containers sharing the same
devices.

On Thu, Aug 11, 2011 at 10:10 AM, Mauras Olivier <oliver.mauras at gmail.com>wrote:

> Also, bandwidth between containers is very bad...
> scp a file doesn't get over 2.1MB/s - On gigabit interface - and drop over
> time.
>
>
> On Thu, Aug 11, 2011 at 9:32 AM, Mauras Olivier <oliver.mauras at gmail.com>wrote:
>
>> So here's my results.
>> On 55 packets transmitted for the mysql request
>> 25 correct checksums
>> 28 incorrect
>>
>> Disabling TSO and GSO doesn't help much, got exact same result
>>
>> As for the macvlan bridge mode how can i check if it's available or not??
>> Would it let things work even if not supported?
>> --- Misc ---
>> Veth pair device: enabled
>> Macvlan: enabled
>> Vlan: enabled
>> File capabilities: enabled
>>
>>
>> Thanks,
>> Olivier
>>
>>
>>
>> On Wed, Aug 10, 2011 at 6:25 PM, Daniel Lezcano <daniel.lezcano at free.fr>wrote:
>>
>>> 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.
>>>
>>
>>
>
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