Re: [Vserver] setting /proc/sys/kernel/shmmax on the guest

From: Daniel Hokka Zakrisson <daniel_at_hozac.com>
Date: Tue 02 Jan 2007 - 19:08:40 GMT
Message-ID: <459AADB8.2030300@hozac.com>

Herbert Poetzl wrote:
> On Tue, Jan 02, 2007 at 03:47:35AM +0100, Daniel Hokka Zakrisson wrote:
>> Herbert Poetzl wrote:
>>> On Mon, Jan 01, 2007 at 02:05:30PM +0100, william Famy wrote:
>>>> -----BEGIN PGP SIGNED MESSAGE-----
>>>> Hash: SHA1
>>>>
>>>> To begin with Happy new year to every vserver guy.
>>> and a happy new year to you too ...
>>>
>>>> I have to extand the shmmax for my guest but I do not manage to do it.
>>>>
>>>> cat /proc/sys/kernel/shmmax
>>>> 134217728
>>>> I have tried the /etc/vserver/host/rlimits
>>>> I have tried to add bcapability
>>>> but I do not manage to go ahead with it.
>>>>
>>>> I've run under 2.6.19.1 with the last devel vserver patch under
>>>> debian etch as host.
>>>>
>>>> Could somebody tell me how to modify the guest config to execute
>>>> "echo 134217728 /proc/sys/kernel/shmmax " for my guest.
>
>>> as 2.6.19.x incorporates the mainline namespace
>>> stuff, you have to set those values from one of
>>> the early guest startup script (e.g. prepre-start)
>>> while you still have 'enough' capabilities ...
>
>> I assume this requires the IPC namespace to be created?
>> That doesn't happen until the context is created, so none of
>> the scripts would work for this particular problem.
>
> hmm, isn't the context supposed to exist in
> the post-start script? if not, please could
> you once and for all clarify which script is
> started when and in what context(s)?

The context will exist in the post-start scripts, but they won't be run
inside the context, and the context will already have lost the extra
capabilities.

>> Having a non-executable one that does something like
>> VSERVER_EXTRA_CMDS=( $_CHAINECHO /proc/sys/kernel/shmmax 134217728 )
>> is probably the only way to make it happen (with current tools).
>
> okay, any plans to allow for such support?
>
>>> also using the sysctl interface instead of the
>>> deprecated procfs one (which might as well be
>>> hidden away :) is advised ...
>>>
>>> maybe special tool support will be added soon,
>>> so please double check with the tool maintainers
>> I guess some nicer way to support it would be required,
>> especially as more of these settings become available.
>
> what do you have in mind ... please share
> your thoughts, as I think those settings _might_
> become essential for certain setups ...

I guess something like /etc/vservers/<guest>/sysctl/<id>/{setting,value}
shouldn't be a problem, should it?

> TIA,
> Herbert
>
>>> HTH,
>>> Herbert
>>>
>>>> Thanks for any help.

-- 
Daniel Hokka Zakrisson
GPG id: 06723412
GPG fingerprint: A455 4DF3 990A 431F FECA  7947 6136 DDA2 0672 3412
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