Messages in this thread | | | Date | Thu, 30 Oct 2014 23:47:40 +0100 | From | Peter Zijlstra <> | Subject | Re: Cache Allocation Technology Design |
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Let me reply to just this one, I'll do the rest tomorrow, need sleeps.
On Thu, Oct 30, 2014 at 06:22:36PM -0400, Tejun Heo wrote:
> > > This controller might not even require the distinction between > > > configured and effective tho? Can't a new child just inherit the > > > parent's configuration and never allow the config to become completely > > > empty? > > > > It can do that. But that still has a problem, there is a mapping in > > hardware which restricts the number of active configurations. The total > > configuration space is larger than the supported active configurations. > > > > So _something_ must fail. The initial proposal was mkdir failing when > > there were more than the hardware supported active config cgroup > > directories. The alternative was on-demand activation where we only > > allocate the hardware resource when the first task gets moved into the > > group -- which then clearly can fail. > > Hmmm... why can't it just refuse creating a different configuration > when its config space is full? Make children inherit the parent's > configuration and refuse config writes which require it to create a > new one if the config space is full. Seems pretty straight-forward. > What am I missing?
We could do that I suppose, there is the one corner case that would not allow, intermediate directories with a restricted config that also have priv restrictions but no actual tasks. Not sure that makes sense though.
Are there any other cases I might have missed?
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