Re: [PATCH 0/5] cpusets: dynamical scheduler domain flags

From: Mike Galbraith
Date: Mon Jul 23 2012 - 00:28:03 EST


On Mon, 2012-07-23 at 10:30 +0800, Michael Wang wrote:
> On 07/21/2012 12:42 AM, Peter Zijlstra wrote:
> > On Tue, 2012-07-17 at 17:03 +0800, Michael Wang wrote:
> >> This patch set provide a way for user to dynamically configure the scheduler
> >> domain flags, which usually to be static.
> >
> > NAK.. you don't get to expose all this nonsense in a 'stable' ABI.
> >
> > You shouldn't need to prod at them to begin with.
>
> So is that means expose those domain flags to user is a bad idea at all?

You can set/clear flags with scripts now, ie domain flags are already
exposed.. as defined by the running kernel.

SD_SHARE_PKG_RESOURCES is a good flag look at. What does flipping that
switch do, and what did it stop doing recently? So yeah, methinks
exporting flags via cpusets is a bad idea. Not only is existence of any
particular flag volatile, functionality behind it is volatile as well,
so having a button to poke does undefined things. (not to mention
non-exclusive sets)

-Mike


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