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For some platforms, for example Broadwell, it doesn't support cycles
for LBR. But the perf always prints cycles:0, it's not necessary.
The patch refactors the LBR info print code and drops the cycles:0.
For example: perf report --branch-history --no-children --stdio
On Broadwell:
--0.91%--__random_r random_r.c:394 (iterations:2)
__random_r random_r.c:360 (predicted:0.0%)
__random_r random_r.c:380 (predicted:0.0%)
__random_r random_r.c:357
On Skylake:
--1.07%--main div.c:39 (predicted:52.4% cycles:1 iterations:17)
main div.c:44 (predicted:52.4% cycles:1)
main div.c:42 (cycles:2)
compute_flag div.c:28 (cycles:2)
compute_flag div.c:27 (cycles:1)
rand rand.c:28 (cycles:1)
rand rand.c:28 (cycles:1)
__random random.c:298 (cycles:1)
__random random.c:297 (cycles:1)
__random random.c:295 (cycles:1)
__random random.c:295 (cycles:1)
__random random.c:295 (cycles:1)
Signed-off-by: Yao Jin <yao.jin@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Link: http://lkml.kernel.org/r/1489046786-10061-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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.