Ev Kontsevoy reported that he can't see the presence of
"/proc/sys/kernel/sched_itmt_enabled" on i9-7900x with Asrock x299
Taichi system even if he enabled "Turbo 3.0" in the BIOS.
The problem is that even if one core max is 200MHz more than others, the
current implementation couldn't enumerate that with the way the system
is configured.
The system by default configured for legacy mode (no HWP or speed shift
technology), in this mode only way we can enumerate via the mail box
interface as implemented in this driver. We were planing to only use
this driver for Broadwell, but we need to extend this because some
Skylake system has same issue as Braodwell systems.
On this system BIOS allows to change to HWP mode, where we expect that
we can enumerate favored core with ACPI-CPPC. But on this system the
core priority is 0xff for all cores in CPPC object. So this is not an
option.
Hence this change allows Skylake systems to be enumerate favored core
similar to Broadwell in legacy mode.
Reported-and-tested-by: Ev Kontsevoy <ev@kontsevoy.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
The Kconfig currently controlling compilation of this code is:
drivers/platform/x86/Kconfig:config INTEL_TURBO_MAX_3
drivers/platform/x86/Kconfig: bool "Intel Turbo Boost Max Technology 3.0 enumeration driver"
...meaning that it currently is not being built as a module by anyone.
Lets remove the couple traces of modular infrastructure use, so that
when reading the driver there is no doubt it is builtin-only.
Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
We also delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.
We do uncover some implicit includes during build coverage that
were hidden behind the module.h which pulls in a lot of dependants.
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
On platforms supporting Intel Turbo Boost Max Technology 3.0, the
maximum turbo frequencies (turbo ratio) of some cores in a CPU package
may be higher than the other cores in the same package. In that case,
better performance can be achieved by making the scheduler prefer to run
tasks on the CPUs with higher max turbo frequencies.
On Intel® Broadwell Xeon systems, it is optional to turn on HWP
(Hardware P-States). When HWP is not turned on, the BIOS doesn't
present required CPPC (Collaborative Processor Performance Control)
tables. This table is used to get the per CPU core maximum performance
ratio and inform scheduler (in cpufreq/intel_pstate driver).
On such systems the maximum performance ratio can be read via over
clocking (OC) mailbox interface for each CPU. This interface is not
architectural and can change for every model of processors.
This driver reads maximum performance ratio of each CPU and set up
the scheduler priority metrics. In this way scheduler can prefer CPU
with higher performance to schedule tasks.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Srinivas Pandruvada