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Subject[PATCH 11/16] perf record: Fix fallback to cpu-clock on ppc
Date
From: David Ahern <dsahern@gmail.com>

perf-record on PPC is not falling back to cpu-clock:

$ perf record -ag -fo /tmp/perf.data -- sleep 1

Error: sys_perf_event_open() syscall returned with 6 (No such device or address). /bin/dmesg may provide additional information.

Fatal: No CONFIG_PERF_EVENTS=y kernel support configured?

The problem is that until 2.6.37 (behavior changed with commit b0a873e)
perf on PPC returns ENXIO when hw_perf_event_init() fails. With this
patch we get the expected behavior:

$ perf record -ag -fo /tmp/perf.data -v -- sleep 1
Old kernel, cannot exclude guest or host samples.
The cycles event is not supported, trying to fall back to cpu-clock-ticks
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.151 MB /tmp/perf.data (~6592 samples) ]

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1336490937-57106-1-git-send-email-dsahern@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-record.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 42e2414..1a9098c 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -242,9 +242,13 @@ try_again:
/*
* If it's cycles then fall back to hrtimer
* based cpu-clock-tick sw counter, which
- * is always available even if no PMU support:
+ * is always available even if no PMU support.
+ *
+ * PPC returns ENXIO until 2.6.37 (behavior changed
+ * with commit b0a873e).
*/
- if (err == ENOENT && attr->type == PERF_TYPE_HARDWARE
+ if ((err == ENOENT || err == ENXIO)
+ && attr->type == PERF_TYPE_HARDWARE
&& attr->config == PERF_COUNT_HW_CPU_CYCLES) {

if (verbose)
--
1.7.9.2.358.g22243


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