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Subject[PATCH 04/19] perf kvm: Fix bug resolving guest kernel syms
Date
From: David Ahern <dsahern@gmail.com>

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>
---
tools/perf/util/map.c | 13 +++++++++++++
tools/perf/util/map.h | 1 +
tools/perf/util/session.c | 1 +
3 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 8668569..16d783d 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;
+}
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index c14c665..03a1e9b 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -151,6 +151,7 @@ struct machine *machines__add(struct rb_root *self, pid_t pid,
struct machine *machines__find_host(struct rb_root *self);
struct machine *machines__find(struct rb_root *self, pid_t pid);
struct machine *machines__findnew(struct rb_root *self, pid_t pid);
+void machines__set_id_hdr_size(struct rb_root *self, u16 id_hdr_size);
char *machine__mmap_name(struct machine *self, char *bf, size_t size);
int machine__init(struct machine *self, const char *root_dir, pid_t pid);
void machine__exit(struct machine *self);
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 90ee39d..8e4f075 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -87,6 +87,7 @@ void perf_session__update_sample_type(struct perf_session *self)
self->sample_id_all = perf_evlist__sample_id_all(self->evlist);
self->id_hdr_size = perf_evlist__id_hdr_size(self->evlist);
self->host_machine.id_hdr_size = self->id_hdr_size;
+ machines__set_id_hdr_size(&self->machines, self->id_hdr_size);
}

int perf_session__create_kernel_maps(struct perf_session *self)
--
1.7.1


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