Re: net namespace plans for 2.6.25 (was Re: Pid namespaces problems)

[Pavel Emelyanov <xemul-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org>]

Daniel Lezcano wrote:
> Denis V. Lunev wrote:
>  > Daniel Lezcano wrote:
>  >> Denis V. Lunev wrote:
>  >>> Daniel Lezcano wrote:
>  >>>
>  >>>>  * the first one is the locking of the network namespace list by
>  >>>> rtnl_lock, so from the timer callback we can not browse the network
>  >>>> namespace list to check the age of the routes. It is a problem I would
>  >>>> like to talk with Denis if he has time
>  >>> From my point of view, the situation is clear. The timer should be
>  >>> per/namespace. The situation is completely different as one in IPv4.
>  >> We thought to make a timer per namespace for ipv6, but we are a little
>  >> afraid for the performances when there will be a lot of containers.
>  >> Anyway, we can do a timer per namespace and optimize that later. I will
>  >> cook a new patch to take into account that for the next week.
>  >
>  > IMHO not a problem. tcp_write_timer is per/socket timer. If this works
>  > efficiently, per/namespace one will work also.
> 
> That's right, this is a good argument. By the way, the amount of work to 
> be done in the tcp_write_timer is perhaps smaller than the one done in 
> the ipv6 routing age check, no ? Anyway, I'm not against a timer per 
> namespace in this case, I already did a try before rolling back to a 
> for_each_net in the gc timer, that changes a little the API, but nothing 

We can easily make the netns list rcu protected to address this issue.
If you're interested, I can prepare a patch tomorrow.

> we can handle easily.
> 
>