Messages in this thread | | | Date | Mon, 3 Aug 2015 15:03:59 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH -v2 6/8] jump_label: Add a new static_key interface |
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On Wed, 29 Jul 2015 10:49:06 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Jul 29, 2015 at 09:19:22AM +0200, Vlastimil Babka wrote: > > > How would one define a static key that's e.g. expected to be mostly false, but > > with initial value of true, e.g. during boot? > > DEFINE_STATIC_KEY_TRUE(blah); > > will get you the true at boot time. > > You'll then want to use: > > if (static_branch_unlikely(&blah)) { > /* code that mostly doesn't happen */ > } > > To indicate you expect it to be false most of the time. And you'll flip > it to false at runtime using: > > static_branch_disable(&blah);
I wonder if static_branch_set_false(&blah) would be a better name to understand. What does "disable" / "enable" mean?
If we declare it "TRUE" when defining it, it only makes sense to change it to "false" later on.
-- Steve
> > If GCC co-operates, the body of the branch will be placed out-of-line, > we'll emit a jump to it by default, but once you disable it, we'll nop > the jump and fall straight through.
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