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Groups > linux.kernel > #1343985
| From | Wang Nan <wangnan0@huawei.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 13/46] perf core: Add backward attribute to perf event |
| Date | 2016-02-26 11:00 +0100 |
| Message-ID | <r6nlM-1cF-9@gated-at.bofh.it> (permalink) |
| References | <r6n2p-13D-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
In perf_event_attr a new bit 'write_backward' is appended to indicate
this event should write ring buffer from its end to beginning.
In perf_output_begin(), prepare ring buffer according this bit.
This patch introduces small overhead into perf_output_begin():
an extra memory read and a conditional branch. Further patch can remove
this overhead by using custom output handler.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
---
include/linux/perf_event.h | 5 +++++
include/uapi/linux/perf_event.h | 3 ++-
kernel/events/core.c | 7 +++++++
kernel/events/ring_buffer.c | 2 ++
4 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index b35a61a..0ce1015 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1029,6 +1029,11 @@ static inline bool has_aux(struct perf_event *event)
return event->pmu->setup_aux;
}
+static inline bool is_write_backward(struct perf_event *event)
+{
+ return !!event->attr.write_backward;
+}
+
extern int perf_output_begin(struct perf_output_handle *handle,
struct perf_event *event, unsigned int size);
extern void perf_output_end(struct perf_output_handle *handle);
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index a3c1903..43fc8d2 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -340,7 +340,8 @@ struct perf_event_attr {
comm_exec : 1, /* flag comm events that are due to an exec */
use_clockid : 1, /* use @clockid for time fields */
context_switch : 1, /* context switch data */
- __reserved_1 : 37;
+ write_backward : 1, /* Write ring buffer from end to beginning */
+ __reserved_1 : 36;
union {
__u32 wakeup_events; /* wakeup every n events */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ae34061..9353154 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8101,6 +8101,13 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
goto out;
/*
+ * Either writing ring buffer from beginning or from end.
+ * Mixing is not allowed.
+ */
+ if (is_write_backward(output_event) != is_write_backward(event))
+ goto out;
+
+ /*
* If both events generate aux data, they must be on the same PMU
*/
if (has_aux(event) && has_aux(output_event) &&
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 37c11c6..80b1fa7 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -233,6 +233,8 @@ out:
int perf_output_begin(struct perf_output_handle *handle,
struct perf_event *event, unsigned int size)
{
+ if (unlikely(is_write_backward(event)))
+ return __perf_output_begin(handle, event, size, true);
return __perf_output_begin(handle, event, size, false);
}
--
1.8.3.4
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[PATCH 00/46] perf tools: Fix and improvements (bpf and overwrite) Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:40 +0100
[PATCH 07/46] perf trace: Print content of bpf-output event Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:40 +0100
[tip:perf/core] perf trace: Print content of bpf-output event tip-bot for Wang Nan <tipbot@zytor.com> - 2016-02-27 10:50 +0100
[PATCH 43/46] perf record: Rename variable to make code clear Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:40 +0100
[PATCH 46/46] perf tools: Don't warn about out of order event if write_backward is used Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 26/46] perf record: Disable buildid cache options by default in switch output mode Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 33/46] perf tools: Operate multiple channels Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 24/46] perf record: Split output into multiple files via '--switch-output' Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 45/46] perf record: Allow generate tracking events at the end of output Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 36/46] perf record: Don't poll on overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 30/46] perf record: Prevent reading invalid data in record__mmap_read Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 31/46] perf tools: Add evlist channel helpers Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 35/46] perf record: Don't read from and poll overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 23/46] perf record: Add '--timestamp-filename' option to append timestamp to output filename Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 25/46] perf record: Force enable --timestamp-filename when --switch-output is provided Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 28/46] perf record: Generate tracking events for process forked by perf Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 21/46] perf record: Turns auxtrace_snapshot_enable into 3 states Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 27/46] perf record: Re-synthesize tracking events after output switching Wang Nan <wangnan0@huawei.com> - 2016-02-26 10:50 +0100
[PATCH 12/46] perf core: Prepare writing into ring buffer from end Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 19/46] perf record: Extract synthesize code to record__synthesize() Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 11/46] perf core: Set event's default overflow_handler Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 13/46] perf core: Add backward attribute to perf event Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 18/46] perf record: Use WARN_ONCE to replace 'if' condition Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 20/46] perf tools: Add perf_data_file__switch() helper Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 17/46] perf tools: Make ordered_events reusable Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 14/46] perf core: Reduce perf event output overhead by new overflow handler Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 08/46] perf data: Support converting data from bpf_perf_event_output() Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 10/46] perf core: Introduce new ioctl options to pause and resume ring buffer Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
Re: [PATCH 10/46] perf core: Introduce new ioctl options to pause and resume ring buffer Arnaldo Carvalho de Melo <acme@kernel.org> - 2016-02-29 16:40 +0100
Re: [PATCH 10/46] perf core: Introduce new ioctl options to pause and resume ring buffer "Wangnan (F)" <wangnan0@huawei.com> - 2016-03-03 03:20 +0100
[PATCH 09/46] perf data: Explicitly set byte order for integer types Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[PATCH 03/46] perf config: Bring perf_default_config to the very beginning at main() Wang Nan <wangnan0@huawei.com> - 2016-02-26 11:00 +0100
[tip:perf/core] perf config: Bring perf_default_config to the very beginning at main() tip-bot for Wang Nan <tipbot@zytor.com> - 2016-02-27 10:50 +0100
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