Skip to content
Snippets Groups Projects
user avatar
Srinivas Pandruvada authored
In some case C1% will be wrong value, when platform doesn't have MSR for
C1 residency.

For example:
Core    CPU     CPU%c1
-       -       100.00
0       0       100.00
0       2       100.00
1       1       100.00
1       3       100.00

But adding Busy% will fix this
Core    CPU     Busy%   CPU%c1
-       -       99.77   0.23
0       0       99.77   0.23
0       2       99.77   0.23
1       1       99.77   0.23
1       3       99.77   0.23

This issue can be reproduced on most of the recent systems including
Broadwell, Skylake and later.

This is because if we don't select Busy% or Avg_MHz or Bzy_MHz then
mperf value will not be read from MSR, so it will be 0. But this
is required for C1% calculation when MSR for C1 residency is not present.
Same is true for C3, C6 and C7 column selection.

So add another define DO_BIC_READ(), which doesn't depend on user
column selection and use for mperf, C3, C6 and C7 related counters.
So when there is no platform support for C1 residency counters,
we still read these counters, if the CPU has support and user selected
display of CPU%c1.

Signed-off-by: default avatarSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
1e9042b9
History
Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.