mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-09-22 09:34:56 +02:00
Kan Liang
95035c5e16
'perf record' will error out if both --delay and LBR are applied. For example: # perf record -D 1000 -a -e cycles -j any -- sleep 2 Error: dummy:HG: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' # A dummy event is added implicitly for initial delay, which has the same configurations as real sampling events. The dummy event is a software event. If LBR is configured, perf must error out. The dummy event will only be used to track PERF_RECORD_MMAP while perf waits for the initial delay to enable the real events. The BRANCH_STACK bit can be safely cleared for the dummy event. After applying the patch: # perf record -D 1000 -a -e cycles -j any -- sleep 2 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.054 MB perf.data (828 samples) ] # Reported-by: Sunil K Pandey <sunil.k.pandey@intel.com> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1531145722-16404-1-git-send-email-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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.