Messages in this thread | | | Date | Tue, 9 Jun 2015 19:06:14 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v2 1/4] x86, mwaitt: add monitorx and mwaitx instruction |
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On Tue, Jun 09, 2015 at 09:44:59AM -0700, Andy Lutomirski wrote: > [1] For those who weren't bitten by this repeatedly, modern Intel CPUs > (at least Sandy Bridge, anyway) will, by default, detect when all > cores are in C1 or deeper, think to themselves "wow, the OS selected > C1 -- it must want a very deep sleep indeed", and put the whole > package into some kind of deep sleep state. The subsequent wakeup > takes tens of milliseconds. Doing this in udelay would be awful.
That's a good point. Reportedly, the current MWAITX enters something between C0 and C1 but the way I understood it, going forward, it will enter deeper sleep states.
So for shallow C-states, your idle enter/exit latency is low enough but I'd guess deeper states would be a problem.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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