On Mon, Jan 20, 2014 at 09:30:21AM +0100, Peter Zijlstra wrote:
> Then make them so. The fact was that most of the mwait idle sites
> were bloody broken. And the single mwait_idle_with_hints() function
> presents a single nice function that does all the required magics.
To stress this a bit more; have a look see at mwwait_idle_with_hints();
it does a whole lot of subtle magic.
- current_{set,clr}_polling*(), these are crucial in not missing and
wrecking NEED_RESCHED state.
- X86_FEATURE_CLFLUSH_MONTIOR quirk
- Does the monitor(); if (!need_resched()) mwait() thing.
All of those are required for a correct and functional idle loop. And
I've seen sites where any or all of the above were missing/broken.
Not unifying the lot into a simple usable function is just stupid --
history has shown people simply cannot be trusted to get this right.
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