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64831a21db
Fixes bug noted by Jiri in https://lkml.org/lkml/2017/6/13/755 and caused by commitd49dadea78("perf tools: Make 'trace' or 'trace_fields' sort key default for tracepoint events") not taking into account that evlist is empty in pipe-mode. Before this commit, pipe mode will only show bogus "100.00% N/A" instead of correct output as follows: $ perf record -o - sleep 1 | perf report -i - # To display the perf.data header info, please use --header/--header-only options. # [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.000 MB - ] # # Total Lost Samples: 0 # # Samples: 8 of event 'cycles:ppH' # Event count (approx.): 145658 # # Overhead Trace output # ........ ............ # 100.00% N/A Correct output, after patch: $ perf record -o - sleep 1 | perf report -i - # To display the perf.data header info, please use --header/--header-only options. # [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.000 MB - ] # # Total Lost Samples: 0 # # Samples: 8 of event 'cycles:ppH' # Event count (approx.): 191331 # # Overhead Command Shared Object Symbol # ........ ....... ................. ................................. # 81.63% sleep libc-2.19.so [.] _exit 13.58% sleep ld-2.19.so [.] do_lookup_x 2.34% sleep [kernel.kallsyms] [k] context_switch 2.34% sleep libc-2.19.so [.] __GI___libc_nanosleep 0.11% perf [kernel.kallsyms] [k] __intel_pmu_enable_a Reported-by: Jiri Olsa <jolsa@kernel.org> Report-Link: https://lkml.kernel.org/r/20170613185422.GA6092@krava Signed-off-by: David Carrillo-Cisneros <davidcc@google.com> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paul Turner <pjt@google.com> Cc: Simon Que <sque@chromium.org> Cc: Stephane Eranian <eranian@google.com> Cc: Wang Nan <wangnan0@huawei.com> Fixes:d49dadea78("perf tools: Make 'trace' or 'trace_fields' sort key default for tracepoint events") Link: https://lkml.kernel.org/r/20170721051157.47331-1-davidcc@google.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.