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CAT test spawns two processes into two different control groups with exclusive schemata. Both the processes alloc a buffer from memory matching their allocated LLC block size and flush the entire buffer out of caches. Since the processes are reading through the buffer only once during the measurement and initially all the buffer was flushed, the test isn't testing CAT. Rewrite the CAT test to allocate a buffer sized to half of LLC. Then perform a sequence of tests with different LLC alloc sizes starting from half of the CBM bits down to 1-bit CBM. Flush the buffer before each test and read the buffer twice. Observe the LLC misses on the second read through the buffer. As the allocated LLC block gets smaller and smaller, the LLC misses will become larger and larger giving a strong signal on CAT working properly. The new CAT test is using only a single process because it relies on measured effect against another run of itself rather than another process adding noise. The rest of the system is set to use the CBM bits not used by the CAT test to keep the test isolated. Replace count_bits() with count_contiguous_bits() to get the first bit position in order to be able to calculate masks based on it. This change has been tested with a number of systems from different generations. Suggested-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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.