From: Wang Nan <wangnan0@huawei.com>
To: <peterz@infradead.org>, <alexei.starovoitov@gmail.com>,
<acme@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, Wang Nan <wangnan0@huawei.com>,
He Kuang <hekuang@huawei.com>,
Alexei Starovoitov <ast@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@redhat.com>,
Brendan Gregg <brendan.d.gregg@gmail.com>,
"Jiri Olsa" <jolsa@kernel.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Namhyung Kim <namhyung@kernel.org>, Zefan Li <lizefan@huawei.com>,
<pi3orama@163.com>
Subject: [PATCH 5/5] perf core: Reduce perf event output overhead by new overflow handler
Date: Mon, 25 Jan 2016 08:33:53 +0000 [thread overview]
Message-ID: <1453710833-2865-6-git-send-email-wangnan0@huawei.com> (raw)
In-Reply-To: <1453710833-2865-1-git-send-email-wangnan0@huawei.com>
By creating onward and backward specific overflow handlers and setting
them according to event's backward setting, normal sampling events
don't need checking backward setting of an event any more.
This is the last patch of backward writing patchset. After this patch,
there's no extra overhead introduced to the fast path of sampling
output.
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 | 17 +++++++++++++++--
kernel/events/core.c | 41 ++++++++++++++++++++++++++++++++++++-----
kernel/events/ring_buffer.c | 12 ++++++++++++
3 files changed, 63 insertions(+), 7 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 54c3fb2..c0335b9 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -830,9 +830,15 @@ extern int perf_event_overflow(struct perf_event *event,
struct perf_sample_data *data,
struct pt_regs *regs);
+extern void perf_event_output_onward(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs);
+extern void perf_event_output_backward(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs);
extern void perf_event_output(struct perf_event *event,
- struct perf_sample_data *data,
- struct pt_regs *regs);
+ struct perf_sample_data *data,
+ struct pt_regs *regs);
extern void
perf_event_header__init_id(struct perf_event_header *header,
@@ -1039,6 +1045,13 @@ static inline bool is_write_backward(struct perf_event *event)
extern int perf_output_begin(struct perf_output_handle *handle,
struct perf_event *event, unsigned int size);
+extern int perf_output_begin_onward(struct perf_output_handle *handle,
+ struct perf_event *event,
+ unsigned int size);
+extern int perf_output_begin_backward(struct perf_output_handle *handle,
+ struct perf_event *event,
+ unsigned int size);
+
extern void perf_output_end(struct perf_output_handle *handle);
extern unsigned int perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8ad22a5..8a25e46 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5541,9 +5541,13 @@ void perf_prepare_sample(struct perf_event_header *header,
}
}
-void perf_event_output(struct perf_event *event,
- struct perf_sample_data *data,
- struct pt_regs *regs)
+static void __always_inline
+__perf_event_output(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs,
+ int (*output_begin)(struct perf_output_handle *,
+ struct perf_event *,
+ unsigned int))
{
struct perf_output_handle handle;
struct perf_event_header header;
@@ -5553,7 +5557,7 @@ void perf_event_output(struct perf_event *event,
perf_prepare_sample(&header, data, event, regs);
- if (perf_output_begin(&handle, event, header.size))
+ if (output_begin(&handle, event, header.size))
goto exit;
perf_output_sample(&handle, &header, data, event);
@@ -5564,6 +5568,30 @@ exit:
rcu_read_unlock();
}
+void
+perf_event_output_onward(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ __perf_event_output(event, data, regs, perf_output_begin_onward);
+}
+
+void
+perf_event_output_backward(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ __perf_event_output(event, data, regs, perf_output_begin_backward);
+}
+
+void
+perf_event_output(struct perf_event *event,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ __perf_event_output(event, data, regs, perf_output_begin);
+}
+
/*
* read event_id
*/
@@ -7874,8 +7902,11 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
if (overflow_handler) {
event->overflow_handler = overflow_handler;
event->overflow_handler_context = context;
+ } else if (is_write_backward(event)){
+ event->overflow_handler = perf_event_output_backward;
+ event->overflow_handler_context = NULL;
} else {
- event->overflow_handler = perf_event_output;
+ event->overflow_handler = perf_event_output_onward;
event->overflow_handler_context = NULL;
}
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 28543e1..ca11809 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -230,6 +230,18 @@ out:
return -ENOSPC;
}
+int perf_output_begin_onward(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size)
+{
+ return __perf_output_begin(handle, event, size, false);
+}
+
+int perf_output_begin_backward(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size)
+{
+ return __perf_output_begin(handle, event, size, true);
+}
+
int perf_output_begin(struct perf_output_handle *handle,
struct perf_event *event, unsigned int size)
{
--
1.8.3.4
next prev parent reply other threads:[~2016-01-25 8:36 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 8:33 [PATCH 0/5] perf core: Read from overwrite ring buffer Wang Nan
2016-01-25 8:33 ` [PATCH 1/5] perf core: Introduce new ioctl options to pause and resume " Wang Nan
2016-01-25 8:33 ` [PATCH 2/5] perf core: Set event's default overflow_handler Wang Nan
2016-01-25 8:33 ` [PATCH 3/5] perf core: Prepare writing into ring buffer from end Wang Nan
2016-01-25 8:33 ` [PATCH 4/5] perf core: Add backward attribute to perf event Wang Nan
2016-01-25 8:33 ` Wang Nan [this message]
2016-01-26 0:24 ` [PATCH 0/5] perf core: Read from overwrite ring buffer Alexei Starovoitov
2016-01-26 8:26 ` Wangnan (F)
-- strict thread matches above, loose matches on Subject: below --
2016-03-14 9:59 [PATCH 0/5] perf core: Support " Wang Nan
2016-03-14 9:59 ` [PATCH 5/5] perf core: Reduce perf event output overhead by new overflow handler Wang Nan
2016-03-23 10:02 ` Peter Zijlstra
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