Messages in this thread | | | Subject | Re: 50 Watt idle power regression bisected to Linux-3.10 | From | Mike Galbraith <> | Date | Sun, 08 Dec 2013 05:57:04 +0100 |
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On Sat, 2013-12-07 at 03:00 -0500, Len Brown wrote: > Hello Thomas, > > An idle WSM-EX box (40 Xeon cores) runs 50 Watts hotter after this patch: > > commit 7d1a941731fabf27e5fb6edbebb79fe856edb4e5 > Author: Thomas Gleixner <tglx@linutronix.de> > Date: Thu Mar 21 22:50:03 2013 +0100 > > x86: Use generic idle loop > > ie. the commit before this patch (aba92c9e2cf3042bf6efc68fa2e4235ba01bf499) > runs at 50 watts less, as do Linux 3.7, 3.8 and 3.9. > > The difference is that the good kernels allow about 98% residence > in the package C6 state, while the bad kernel is so noisy that it > gets into pc6 0% of the time. > (indeed, even core C6 is reduced to about 50% from over 99%)
FWIW, my little x3550 (E5620) box is spending ~99% of its time in C3 per powertop, deepest state it has. It took a big hit from 69a37bea as well as 7d1a9417, but with revert of 69a37bea, and addition of ea811747, it's fairly close to 3.7 in fastpath weight, and greenery _seems_ fine.
-Mike
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