From: Dongsheng Yang <yangds.f...@cn.fujitsu.com>
Currently, if we use perf kvm --guestkallsyms --guestmodules report, we
can not get the perf information from perf data file. 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 was introduced by 207b57926 (perf kvm: Fix regression with guest
machine creation).
In original code, it uses perf_session__find_machine(), it means we deliver
symbol to machine
which has the same pid, if no machine found, deliver it to *default* guest. But
if we use
perf_session__findnew_machine() here, if no machine was found, new machine with
pid will be built
and added. Then the default guest which with pid == 0 will never get a symbol.
And because the new machine initialized here has no kernel map created, the
symbol delivered to
it will be marked as "unknown".
This patch here is to revert commit 207b57926 and fix the SEGFAULT bug in
another way.
Verification 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.f...@cn.fujitsu.com>
Acked-by: David Ahern <dsah...@gmail.com>
Cc: sta...@vger.kernel.org # 3.3+
Cc: David Ahern <dsah...@gmail.com>
Link:
http://lkml.kernel.org/r/1387564907-3045-1-git-send-email-yangds.f...@cn.fujitsu.com
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.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 cbacaab3e9c4..d3a857be9682 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -830,6 +830,7 @@ 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) ||
@@ -842,7 +843,11 @@ 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;
--
1.8.1.4
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