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

[Mauras Olivier]

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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