perf kvm: Fix bug resolving guest kernel syms

Guest kernel symbols are not resolved despite passing the information
needed to resolve them. e.g.,

perf kvm --guest --guestmount=/tmp/guest-mount record -a -- sleep 1
perf kvm --guest --guestmount=/tmp/guest-mount report --stdio

    36.55%  [guest/11399]  [unknown]         [g] 0xffffffff81600bc8
    33.19%  [guest/10474]  [unknown]         [g] 0x00000000c0116e00
    30.26%  [guest/11094]  [unknown]         [g] 0xffffffff8100a288
    43.69%  [guest/10474]  [unknown]         [g] 0x00000000c0103d90
    37.38%  [guest/11399]  [unknown]         [g] 0xffffffff81600bc8
    12.24%  [guest/11094]  [unknown]         [g] 0xffffffff810aa91d
     6.69%  [guest/11094]  [unknown]         [u] 0x00007fa784d721c3

which is just pathetic.

After a maddening 2 days sifting through perf minutia I found it --
id_hdr_size is not initialized for guest machines. This shows up on the
report side as random garbage for the cpu and timestamp, e.g.,

29816 7310572949125804849 0x1ac0 [0x50]: PERF_RECORD_MMAP ...

That messes up the sample sorting such that synthesized guest maps are
processed last.

With this patch you get a much more helpful report:

  12.11%  [guest/11399]  [guest.kernel.kallsyms.11399]  [g] irqtime_account_process_tick
  10.58%  [guest/11399]  [guest.kernel.kallsyms.11399]  [g] run_timer_softirq
   6.95%  [guest/11094]  [guest.kernel.kallsyms.11094]  [g] printk_needs_cpu
   6.50%  [guest/11094]  [guest.kernel.kallsyms.11094]  [g] do_timer
   6.45%  [guest/11399]  [guest.kernel.kallsyms.11399]  [g] idle_balance
   4.90%  [guest/11094]  [guest.kernel.kallsyms.11094]  [g] native_read_tsc
    ...

v2:
- changed rbtree walk to use rb_first per Namhyung's suggestion

Tested-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1342826756-64663-5-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 8668569d4b2a..16d783d322b6 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -729,3 +729,16 @@ char *machine__mmap_name(struct machine *self, char *bf, size_t size)
 
 	return bf;
 }
+
+void machines__set_id_hdr_size(struct rb_root *machines, u16 id_hdr_size)
+{
+	struct rb_node *node;
+	struct machine *machine;
+
+	for (node = rb_first(machines); node; node = rb_next(node)) {
+		machine = rb_entry(node, struct machine, rb_node);
+		machine->id_hdr_size = id_hdr_size;
+	}
+
+	return;
+}