On 09/05/2012 01:26 PM, Peter Zijlstra wrote: > On Wed, 2012-09-05 at 13:12 +0400, Glauber Costa wrote: >> On 09/05/2012 01:11 PM, Tejun Heo wrote: >>> Hello, Peter. >>> >>> On Wed, Sep 05, 2012 at 11:06:33AM +0200, Peter Zijlstra wrote: >>>> *confused* I always thought that was exactly what you meant with unified >>>> hierarchy. >>> >>> No, I never counted out differing granularity. >>> >> >> Can you elaborate on which interface do you envision to make it work? >> They will clearly be mounted in the same hierarchy, or as said >> alternatively, comounted. >> >> If you can turn them on/off on a per-subtree basis, which interface >> exactly do you propose for that? > > I wouldn't, screw that. That would result in the exact same problem > we're trying to fix. I want a single hierarchy walk, that's expensive > enough. > >> Would a pair of cgroup core files like available_controllers and >> current_controllers are a lot of drivers do, suffice? > > No.. its not a 'feature' I care to support for 'my' controllers. > > I simply don't want to have to do two (or more) hierarchy walks for > accounting on every schedule event, all that pointer chasing is stupidly > expensive. > You wouldn't have to do more than one hierarchy walks for that. What Tejun seems to want, is the ability to not have a particular controller at some point in the tree. But if they exist, they are always together. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>