Re: [RFC/PATCH 1/8]: CGroup Files: Add locking mode to cgroups control files

[Paul Menage]

On Tue, May 13, 2008 at 2:32 PM, Andrew Morton
<akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
>  But do we ever expect that cgroup_mutex will be taken with much
>  frequency, or held for much time?  If it's only taken during, say,
>  configuration of a group or during a query of that configuration then
>  perhaps we'll be OK.

I'm not so worried about contention on the userspace configuration
side - more the case of configuration operations stalling
subsystem-initiated operations. An example of that would be the case
of hierarchical reclaim in the memory controller, where it needs to be
able to traverse up and down the hierarchy without the hierarchy
changing under its feet.

I'll dump the implicit lock_mode support and make it more explicit in
the subsystem handlers.

Paul
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