[PATCH] perf tools: Fix bug for perf kvm report without guestmount.

Dongsheng Yang
2013-12-06T08:35:20Z

Currently, if we use perf kvm --guestkallsyms --guestmodules report,
we can not get the perf information from perf data file. The all sample
are shown as unknown.

Reproducing steps:
# perf kvm --guestkallsyms /tmp/kallsyms --guestmodules /tmp/modules record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.624 MB perf.data.guest (~27260 samples) ]
# perf kvm --guestkallsyms /tmp/kallsyms --guestmodules /tmp/modules report |grep %
100.00% [guest/6471] [unknown] [g] 0xffffffff8164f330

This bug is caused when delivery sample. We use perf_session__find_machine_for_cpumode() to find
the machine, and it call perf_session__findnew_machine(). Then we will delivery the sample to a
new machine without kernel mapped.

This patch changes perf_session__findnew_machine() to perf_session__find_machine(), so the sample
will be deliveried to default guest machine if there is no machine specified for it.

Verify steps:
# ./perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules record -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.651 MB perf.data.guest (~28437 samples) ]
# ./perf kvm --guestkallsyms /home/kallsyms --guestmodules /home/modules report |grep %
22.64% :6471 [guest.kernel.kallsyms] [g] update_rq_clock.part.70
19.99% :6471 [guest.kernel.kallsyms] [g] d_free
18.46% :6471 [guest.kernel.kallsyms] [g] bio_phys_segments
16.25% :6471 [guest.kernel.kallsyms] [g] dequeue_task
12.78% :6471 [guest.kernel.kallsyms] [g] __switch_to
7.91% :6471 [guest.kernel.kallsyms] [g] scheduler_tick
1.75% :6471 [guest.kernel.kallsyms] [g] native_apic_mem_write
0.21% :6471 [guest.kernel.kallsyms] [g] apic_timer_interrupt

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
---
tools/perf/util/session.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 8a7da6f..1770f2f 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -851,6 +851,7 @@ static struct machine *
struct perf_sample *sample)
{
const u8 cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;
+ struct machine *machine;

if (perf_guest &&
((cpumode == PERF_RECORD_MISC_GUEST_KERNEL) ||
@@ -863,7 +864,11 @@ static struct machine *
else
pid = sample->pid;

- return perf_session__findnew_machine(session, pid);
+ machine = perf_session__find_machine(session, pid);
+ if (!machine)
+ machine = perf_session__findnew_machine(session,
+ DEFAULT_GUEST_KERNEL_ID);
+ return machine;
}

return &session->machines.host;
--
1.8.2.1