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Re: The issues for agreeing on a virtualization/namespaces implementation. [message #1701 is a reply to message #1700]

Mon, 20 February 2006 12:40

Herbert Poetzl
Messages: 239
Registered: February 2006

Senior Member

On Mon, Feb 20, 2006 at 03:11:32PM +0300, Kirill Korotaev wrote:
> >>The questions seem to break down into:
> >>1) Where do we put the references to the different namespaces?
> >> - Do we put the references in a struct container that we reference
> >>from struct task_struct?
> >> - Do we put the references directly in struct task_struct?
> >
> >
> >You "cache" task_struct->container->hotsubsys under
> >task_struct->hotsubsys.
> >We don't change containers other then at clone time, so no coherency
> >issue here !!!!
> >Which subsystems pointers to "cache", should be agreed by the experts,
> >but first approach should always not to cache and go through the container.
> agreed. I see no much reason to cache it and make tons of the same
> pointers in all the tasks. Only if needed.

> Also, in OpenVZ container has many fields intergrated inside, so there
> is no additional dereference, but task->container->subsys_field

as does Linux-VServer currently, but do you have
any proof that putting all the fields together in
one big structure actually has any (dis)advantage
over separate structures?

> >>2) What is the syscall interface to create these namespaces?
> >> - Do we add clone flags? (Plan 9 style)
> >Like that approach .. flexible .. particular when one has well
> >specified namespaces.
> mmm, how do you plan to pass additional flags to clone()?
> e.g. strong or weak isolation of pids?

do you really have to pass them at clone() time?
would shortly after be more than enough?
what if you want to change those properties later?

> another questions:
> how do you plan to meet the dependancies between namespaces?
> e.g. conntracks require netfilters to be initialized.
> network requires sysctls and proc to be initialized and so on.
> do you propose to track all this in clone()? huh...

this is missing isolation/virtualization, and I guess
it has to be done to make those spaces useful ...

> >> - Do we add a syscall (similar to setsid) per namespace?
> >> (Traditional unix style)?
> can be so...
>
> >> - Do we in addition add syscalls to manipulate containers
> >> generically?
> >>
> >> I don't think having a single system call to create a container
> >> and a new instance of each namespace is reasonable as that does
> >> not give us a path into the future when we create yet another
> >> namespace.
> >Agreed.
> why do you think so?

> this syscalls will start handling this new namespace and that's all.
> this is not different from many syscalls approach.

well, let's defer the 'how amny syscalls' issue to
a later time, when we know what we want to implement :)

> >>4) How do we implement each of these namespaces?
> >> Besides being maintainable are there other constraints?
> >>
> >Good question... at least with PID and FS two are there ..
> >>
> >>6) How do we do all of this efficiently without a noticeable impact on
> >> performance?
> >> - I have already heard concerns that I might be introducing cache
> >> line bounces and thus increasing tasklist_lock hold time.
> >> Which on big way systems can be a problem.

> this is nothing compared to hierarchy operations.
> BTW, heirarchy also introduces complicated resource accounting,
> sometimes making it even impossible.

well, depends how you do it ...

best,
Herbert

> Kirill

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[Message index]

		[PATCH 1/4] Virtualization/containers: introduction By: Kirill Korotaev on Mon, 06 February 2006 21:55
		[PATCH 2/4] Virtualization/containers: CONFIG_CONTAINER By: Kirill Korotaev on Mon, 06 February 2006 22:10
		[PATCH 3/4] Virtualization/containers: UID hash By: Kirill Korotaev on Mon, 06 February 2006 22:15
		[PATCH 4/4] Virtualization/containers: uts name By: Kirill Korotaev on Mon, 06 February 2006 22:20
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Dave Hansen on Mon, 06 February 2006 23:00
		Re: [PATCH 1/4] Virtualization/containers: introduction By: dev on Tue, 07 February 2006 12:22
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 03:34
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Rik van Riel on Tue, 07 February 2006 03:40
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Sam Vilain on Tue, 07 February 2006 06:30
		Re: [PATCH 1/4] Virtualization/containers: introduction By: dev on Tue, 07 February 2006 11:49
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 14:31
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 15:42
		Re: [PATCH 1/4] Virtualization/containers: introduction By: dev on Tue, 07 February 2006 16:16
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 17:20
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Sam Vilain on Tue, 07 February 2006 22:43
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Hubertus Franke on Tue, 07 February 2006 16:57
		Re: [PATCH 1/4] Virtualization/containers: introduction By: serue on Tue, 07 February 2006 20:19
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Hubertus Franke on Tue, 07 February 2006 20:46
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 22:00
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Hubertus Franke on Tue, 07 February 2006 22:19
		The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Tue, 07 February 2006 22:06
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Hubertus Franke on Tue, 07 February 2006 23:35
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Alexey Kuznetsov on Wed, 08 February 2006 00:43
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 02:49
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: serue on Wed, 08 February 2006 03:36
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 05:23
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Hubertus Franke on Wed, 08 February 2006 14:40
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 17:46
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 22:28
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: serue on Wed, 08 February 2006 15:17
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: serue on Wed, 08 February 2006 18:03
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: dev on Mon, 20 February 2006 12:08
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Herbert Poetzl on Mon, 20 February 2006 12:40
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: dev on Mon, 20 February 2006 14:25
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Herbert Poetzl on Mon, 20 February 2006 15:16
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Andi Kleen on Mon, 20 February 2006 15:17
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 03:52
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Herbert Poetzl on Wed, 08 February 2006 04:37
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 04:46
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Herbert Poetzl on Wed, 08 February 2006 04:56
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: serue on Wed, 08 February 2006 14:38
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Hubertus Franke on Wed, 08 February 2006 14:51
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: dev on Wed, 08 February 2006 15:34
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Hubertus Franke on Wed, 08 February 2006 15:57
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Herbert Poetzl on Wed, 08 February 2006 19:02
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Wed, 08 February 2006 16:48
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Hubertus Franke on Wed, 08 February 2006 18:31
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Dave Hansen on Wed, 08 February 2006 20:21
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: serue on Wed, 08 February 2006 21:22
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Thu, 09 February 2006 05:41
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: Kyle Moffett on Thu, 09 February 2006 04:45
		Re: The issues for agreeing on a virtualization/namespaces implementation. By: ebiederm on Thu, 09 February 2006 22:25
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Sam Vilain on Tue, 07 February 2006 22:58
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Hubertus Franke on Tue, 07 February 2006 23:18
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Wed, 08 February 2006 05:03
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Hubertus Franke on Wed, 08 February 2006 14:13
		Re: [PATCH 1/4] Virtualization/containers: introduction By: dev on Wed, 08 February 2006 15:42
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Wed, 08 February 2006 16:39
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Kevin Fox on Wed, 08 February 2006 02:08
		Re: [PATCH 1/4] Virtualization/containers: introduction By: dev on Wed, 08 February 2006 15:35
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Wed, 08 February 2006 17:16
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Dave Hansen on Wed, 08 February 2006 20:43
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Wed, 08 February 2006 21:04
		Re: [PATCH 1/4] Virtualization/containers: introduction By: dev on Tue, 07 February 2006 12:12
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 14:06
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Rik van Riel on Tue, 07 February 2006 14:52
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Tue, 07 February 2006 15:13
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Sam Vilain on Wed, 08 February 2006 01:16
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Paul Jackson on Wed, 08 February 2006 04:21
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Thu, 09 February 2006 00:24
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Jeff Dike on Thu, 09 February 2006 02:18
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Thu, 09 February 2006 03:16
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Hubertus Franke on Thu, 09 February 2006 16:38
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Jeff Dike on Thu, 09 February 2006 17:47
		Re: [PATCH 1/4] Virtualization/containers: introduction By: Sam Vilain on Thu, 09 February 2006 22:09
		Re: [PATCH 1/4] Virtualization/containers: introduction By: ebiederm on Thu, 09 February 2006 21:56

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