linux/drivers/idle
Len Brown 40e2d7f9b5 x86 idle: Repair large-server 50-watt idle-power regression
Linux 3.10 changed the timing of how thread_info->flags is touched:

	x86: Use generic idle loop
	(7d1a941731)

This caused Intel NHM-EX and WSM-EX servers to experience a large number
of immediate MONITOR/MWAIT break wakeups, which caused cpuidle to demote
from deep C-states to shallow C-states, which caused these platforms
to experience a significant increase in idle power.

Note that this issue was already present before the commit above,
however, it wasn't seen often enough to be noticed in power measurements.

Here we extend an errata workaround from the Core2 EX "Dunnington"
to extend to NHM-EX and WSM-EX, to prevent these immediate
returns from MWAIT, reducing idle power on these platforms.

While only acpi_idle ran on Dunnington, intel_idle
may also run on these two newer systems.
As of today, there are no other models that are known
to need this tweak.

Link: http://lkml.kernel.org/r/CAJvTdK=%2BaNN66mYpCGgbHGCHhYQAKx-vB0kJSWjVpsNb_hOAtQ@mail.gmail.com
Signed-off-by: Len Brown <len.brown@intel.com>
Link: http://lkml.kernel.org/r/baff264285f6e585df757d58b17788feabc68918.1387403066.git.len.brown@intel.com
Cc: <stable@vger.kernel.org> # 3.12.x, 3.11.x, 3.10.x
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2013-12-19 11:47:39 -08:00
..
Kconfig drivers/idle: remove depends on CONFIG_EXPERIMENTAL 2013-01-21 14:52:43 -08:00
Makefile intel_idle: native hardware cpuidle driver for latest Intel processors 2010-05-28 14:26:20 -04:00
i7300_idle.c intel_idle: Convert i7300_idle_lock to raw_spinlock 2013-02-19 08:42:47 +01:00
intel_idle.c x86 idle: Repair large-server 50-watt idle-power regression 2013-12-19 11:47:39 -08:00