acb65150a4
With the hardware TopDown metrics feature, sample-read feature should be supported for a topdown group, e.g., sample a non-topdown event and read a topdown metric group. But the current perf record code errors out. For a topdown metric group, the slots event must be the leader of the group, but the leader slots event doesn't support sampling. To support sample-read the topdown metric group, use the 2nd event of the group as the "leader" for the purposes of sampling. Only the platform with Topdown metic feature supports sample-read the topdown group. Add arch_topdown_sample_read() to indicate whether the topdown group supports sample-read. Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Acked-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20200911144808.27603-3-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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.