968f03158d
[ Upstream commit 95035c5e167ae6e740b1ddd30210ae0eaf39a5db ] '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> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.