perf list: Do event name substring search as last resort when no events found

perf list: Do event name substring search as last resort when no events found

Before:

  # perf list _alloc_ | head -10
  #

After:

  # perf list _alloc_ | head -10
    ext4:ext4_alloc_da_blocks                          [Tracepoint event]
    ext4:ext4_get_implied_cluster_alloc_exit           [Tracepoint event]
    kmem:kmem_cache_alloc_node                         [Tracepoint event]
    kmem:mm_page_alloc_extfrag                         [Tracepoint event]
    kmem:mm_page_alloc_zone_locked                     [Tracepoint event]
    xen:xen_mmu_alloc_ptpage                           [Tracepoint event]
  #

And it works for all types of events:

  # perf list br

  List of pre-defined events (to be used in -e):

    branch-instructions OR branches                    [Hardware event]
    branch-misses                                      [Hardware event]

    branch-load-misses                                 [Hardware cache event]
    branch-loads                                       [Hardware cache event]

    branch-instructions OR cpu/branch-instructions/    [Kernel PMU event]
    branch-misses OR cpu/branch-misses/                [Kernel PMU event]

    filelock:break_lease_block                         [Tracepoint event]
    filelock:break_lease_noblock                       [Tracepoint event]
    filelock:break_lease_unblock                       [Tracepoint event]
    syscalls:sys_enter_brk                             [Tracepoint event]
    syscalls:sys_exit_brk                              [Tracepoint event]

  #

Suggested-by: Ingo Molnar <mingo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-qieivl18jdemoaghgndj36e6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>