On Mon, Mar 05, 2007 at 07:39:37PM +0100, Herbert Poetzl wrote:
> > Thats why nsproxy has pointers to resource control objects, rather
> > than embedding resource control information in nsproxy itself.
>
> which makes it a (name)space, no?
I tend to agree, yes!
> > This will let different nsproxy structures share the same resource
> > control objects (ctlr_data) and thus be governed by the same
> > parameters.
>
> as it is currently done for vfs, uts, ipc and soon
> pid and network l2/l3, yes?
yes (by vfs do you mean mnt_ns?)
> > Where else do you think the resource control information for a
> > container should be stored?
>
> an alternative for that is to keep the resource
> stuff as part of a 'context' structure, and keep
> a reference from the task to that (one less
> indirection, as we had for vfs before)
something like:
struct resource_context {
int cpu_limit;
int rss_limit;
/* all other limits here */
}
struct task_struct {
...
struct resource_context *rc;
}
?
With this approach, it makes it hard to have task-grouping that are
unique to each resource.
For ex: lets say that CPU and Memory needs to be divided as follows:
CPU : C1 (70%), C2 (30%)
Mem : M1 (60%), M2 (40%)
Tasks T1, T2, T3, T4 are assigned to these resource classes as follows:
C1 : T1, T3
C2 : T2, T4
M1 : T1, T4
M2 : T2, T3
We had a lengthy discussion on this requirement here:
http://lkml.org/lkml/2006/11/6/95
http://lkml.org/lkml/2006/11/1/239
Linus also has expressed a similar view here:
http://lwn.net/Articles/94573/
Paul Menage's (and its clone rcfs) patches allows this flexibility by simply
mounting different hierarchies:
mount -t container -o cpu none /dev/cpu
mount -t container -o mem none /dev/mem
The task-groups created under /dev/cpu can be completely independent of
task-groups created under /dev/mem.
Lumping together all resource parameters in one struct (like
resource_context above) makes it difficult to provide this feature.
Now can we live w/o this flexibility? Maybe, I don't know for sure.
Since (stability of) user-interface is in question, we need to take a
carefull decision here.
> > then other derefences (->ctlr_data[] and ->limit) should be fast, as
> > they should be in the cache?
>
> please provide real world numbers from testing ...
What kind of testing did you have in mind?
--
Regards,
vatsa
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