Messages in this thread | | | Subject | Re: fast path cycle muncher (vmstat: make vmstat_updater deferrable again and shut down on idle) | From | Mike Galbraith <> | Date | Tue, 26 Jan 2016 19:31:18 +0100 |
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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
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