Re: [PATCH 6/7] containers (V7): BeanCounters over generic process containers

[Pavel Emelianov <xemul@sw.ru>]

Paul Menage wrote:
> On 2/13/07, Pavel Emelianov <xemul@sw.ru> wrote:
>> menage@google.com wrote:
>> > This patch implements the BeanCounter resource control abstraction
>> > over generic process containers. It contains the beancounter core
>> > code, plus the numfiles resource counter. It doesn't currently contain
>> > any of the memory tracking code or the code for switching beancounter
>> > context in interrupts.
>>
>> Numfiles is not the most interesting place in beancounters.
>> Kmemsize accounting is much more important actually.
> 
> Right, but the memory accouting was a much bigger and more intrusive
> patch than I wanted to include as an example.

I know it, but numfile doesn't show how good this
infrastructure is.

>>
>> I have already pointed out the fact that this place
>> will hurt performance too much. If we have some context
>> on task this context must
>>   1. be get-ed without any locking
> 
> Would you also be happy with the restriction that a task couldn't be
> moved in/out of a beancounter container by any task other than itself?

I have implementation that moves arbitrary task :)
May be we can do context (container-on-task) handling lockless?

> If so, the beancounter can_attach() method could simply return false
> if current != tsk, and then you'd not need to worry about locking in
> this situation.

I may not, but this patch contains locking that is not good
even for example.

>>   2. be settable to some temporary one without
>>      locking as well
> 
> I thought that we solved that problem by having a tmp_bc field in the
> task_struct that would take precedence over the main bc if it was
> non-null?

Of course, but I'm commenting this patchset which doesn't have
this facility.

> Paul
>