On Mon, 2016-11-28 at 09:56 +0100, Borislav Petkov wrote:

On Tue, Nov 22, 2016 at 12:23:56PM -0800, Tim Chen wrote:

quoted

Intel Turbo Boost Max Technology 3.0 (ITMT) feature
allows some cores to be boosted to higher turbo
frequency than others.

Add /proc/sys/kernel/sched_itmt_enabled so operator
can enable/disable scheduling of tasks that favor cores
with higher turbo boost frequency potential.

By default, system that is ITMT capable and single
socket has this feature turned on.  It is more likely
to be lightly loaded and operates in Turbo range.

When there is a change in the ITMT scheduling operation
desired, a rebuild of the sched domain is initiated
so the scheduler can set up sched domains with appropriate
flag to enable/disable ITMT scheduling operations.

Co-developed-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Tim Chen <redacted>
---
 arch/x86/include/asm/topology.h |   7 ++-
 arch/x86/kernel/itmt.c          | 108 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 112 insertions(+), 3 deletions(-)

...

quoted

+/*
+ * Boolean to control whether we want to move processes to cpu capable
+ * of higher turbo frequency for cpus supporting Intel Turbo Boost Max
+ * Technology 3.0.
+ *
+ * It can be set via /proc/sys/kernel/sched_itmt_enabled
+ */sched_autogroup_enabled
+unsigned int __read_mostly sysctl_sched_itmt_enabled;

Err, can we not have the boolean in the name itself?

I.e., have it called sysctl_sched_itmt and 1 means enabled and 0
disabled? I.e., the classic thing. :)

Ditto for the sysctl name?

I am following the convention in /proc/sys/kernel/sched_autogroup_enabled
and sysctl_sched_autogroup_enabled that's also in /proc/sys/kernel.

Thanks.

Tim