On 04/24/2012 12:02 PM, Christoph Lameter wrote:
On Mon, 23 Apr 2012, Glauber Costa wrote:
This will allow us to call destroy() without holding the
cgroup_mutex(). Other important updates inside update_flags()
are protected by the callback_mutex.
We could protect this variable with the callback_mutex as well,
as suggested by Li Zefan, but we need to make sure we are protected
by that mutex at all times, and some of its updates happen inside the
cgroup_mutex - which means we would deadlock.
Would this not also be a good case to introduce static branching?
number_of_cpusets is used to avoid going through unnecessary processing
should there be no cpusets in use.
Well,
static branches comes with a set of problems themselves, so I usually
prefer to use them only in places where we don't want to pay even a
cache miss if we can avoid, or a function call, or anything like that -
like the slub cache alloc as you may have seen in my kmem memcg series.
It doesn't seem to be the case here.
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