On Tue, 2016-01-26 at 10:25 -0600, Christoph Lameter wrote:
> On Mon, 25 Jan 2016, Michal Hocko wrote:
>
> > > Why would the deferring cause this overhead?
> >
> > I guess the profile speaks for itself, doesn't it?
>
> But the system is going idle? Why would this impact performance?
We enter/exit idle a lot.
Your reluctance to move it seem to suggest that 99.99% of CPUs on the
planet chewing up cycles (measured) doing what for most is useless work
on every micro-idle is a perfectly fine price to pay to ensure that
.01% (or whatever tiny minority) get what they want.
I disagree. You're burning electrons for no benefit at all to me on my
box. You want to do high speed trading, that's fine, but I expect my
box to be able to pop in and out of idle without having to pay a toll
to the high speed trading bandits of the world, thank you very much.
This specialty thing does not belong in the generic fast path.
-Mike
