On Fri, 2020-01-24 at 10:00 -0700, Jonathan Corbet wrote: > On Sun, 12 Jan 2020 20:01:43 -0800 > Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote: > > > Added documentation for the attributes to control uncore frequency > > selection. > > > > Signed-off-by: Srinivas Pandruvada < > > srinivas.pandruvada@xxxxxxxxxxxxxxx> > > --- > > v2: > > - Split the documentation patch to another patch to merge via > > different > > tree > > Which tree did you have in mind? PM stuff tends to go through > Rafael's > tree, normally, which is fine. Linux PM tree is fine. I will add necessary --to and --cc to my next version of the patch with the suggested changes from you. Thanks, Srinivas > > > Documentation/admin-guide/pm/intel_uncore.rst | 23 > > +++++++++++++++++++ > > .../admin-guide/pm/working-state.rst | 1 + > > 2 files changed, 24 insertions(+) > > create mode 100644 Documentation/admin-guide/pm/intel_uncore.rst > > > > diff --git a/Documentation/admin-guide/pm/intel_uncore.rst > > b/Documentation/admin-guide/pm/intel_uncore.rst > > new file mode 100644 > > index 000000000000..d75be65fb16a > > --- /dev/null > > +++ b/Documentation/admin-guide/pm/intel_uncore.rst > > @@ -0,0 +1,23 @@ > > +.. SPDX-License-Identifier: GPL-2.0 > > + > > +========================================================= > > +Intel® Uncore Frequency Selection > > I would really like to avoid adding ® symbols throughout the docs. I > get > grief for non-ASCII symbols that actually have a need to be there; > this > isn't one of those. > > > +========================================================= > > + > > +The uncore frequency in the Intel(R) hardware is selected based on > > internal heuristics, which uses the current selected performance > > state and various system power constraints. In majority of the > > cases this selection is the most optimal, so there is no need for > > placing external constraints from the Operating System. > > I would say that this violates the 80-character limit by a character > or > two... The entire patch has this problem. > > > + > > +But there are some customers who wants less jitters from dynamic > > uncore frequency selection. For them, power saving is much lower > > priority than consistent performance. Currently these customers > > uses MSR 0x620, to place hard limits on the maximum and the minimum > > uncore frequency. They can now use Linux sysfs to place these > > limits and also have additional capability to place hard limits > > under power constraint scenario. > > less jitter (singular) > > > + > > +The Uncore frequency section attributes are present under > > "/sys/devices/system/cpu/intel_uncore_frequency". > > +The scope of these attributes is per die in multi-die systems or > > package wide in non multi-die systems. There is a unique folder for > > each die or package. For example: > > +"package_00_die_00" for package 0 and die 0. > > This may not render as you would like; use an RST literal block here. > > Thanks, > > jon >
