Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1339253
| From | Wang Nan <wangnan0@huawei.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 15/48] perf core: Prepare writing into ring buffer from end |
| Date | 2016-02-22 10:20 +0100 |
| Message-ID | <r4UOT-3pt-37@gated-at.bofh.it> (permalink) |
| References | <r4UOR-3pt-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Convert perf_output_begin to __perf_output_begin and make the later
function able to write records from the end of the ring buffer.
Following commits will utilize the 'backward' flag.
This patch doesn't introduce any extra performance overhead since we
use always_inline.
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
---
kernel/events/ring_buffer.c | 42 ++++++++++++++++++++++++++++++++++++------
1 file changed, 36 insertions(+), 6 deletions(-)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 22e1a47..37c11c6 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -102,8 +102,21 @@ out:
preempt_enable();
}
-int perf_output_begin(struct perf_output_handle *handle,
- struct perf_event *event, unsigned int size)
+static bool __always_inline
+ring_buffer_has_space(unsigned long head, unsigned long tail,
+ unsigned long data_size, unsigned int size,
+ bool backward)
+{
+ if (!backward)
+ return CIRC_SPACE(head, tail, data_size) >= size;
+ else
+ return CIRC_SPACE(tail, head, data_size) >= size;
+}
+
+static int __always_inline
+__perf_output_begin(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size,
+ bool backward)
{
struct ring_buffer *rb;
unsigned long tail, offset, head;
@@ -146,9 +159,12 @@ int perf_output_begin(struct perf_output_handle *handle,
do {
tail = READ_ONCE(rb->user_page->data_tail);
offset = head = local_read(&rb->head);
- if (!rb->overwrite &&
- unlikely(CIRC_SPACE(head, tail, perf_data_size(rb)) < size))
- goto fail;
+ if (!rb->overwrite) {
+ if (unlikely(!ring_buffer_has_space(head, tail,
+ perf_data_size(rb),
+ size, backward)))
+ goto fail;
+ }
/*
* The above forms a control dependency barrier separating the
@@ -162,9 +178,17 @@ int perf_output_begin(struct perf_output_handle *handle,
* See perf_output_put_handle().
*/
- head += size;
+ if (!backward)
+ head += size;
+ else
+ head -= size;
} while (local_cmpxchg(&rb->head, offset, head) != offset);
+ if (backward) {
+ offset = head;
+ head = (u64)(-head);
+ }
+
/*
* We rely on the implied barrier() by local_cmpxchg() to ensure
* none of the data stores below can be lifted up by the compiler.
@@ -206,6 +230,12 @@ out:
return -ENOSPC;
}
+int perf_output_begin(struct perf_output_handle *handle,
+ struct perf_event *event, unsigned int size)
+{
+ return __perf_output_begin(handle, event, size, false);
+}
+
unsigned int perf_output_copy(struct perf_output_handle *handle,
const void *buf, unsigned int len)
{
--
1.8.3.4
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 00/48] perf tools: Bugfix, BPF improvements and overwrite ring buffer support Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 15/48] perf core: Prepare writing into ring buffer from end Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 28/48] perf record: Disable buildid cache options by default in switch output mode Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 09/48] perf tools: Pass tracepoint options to BPF script Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 27/48] perf record: Force enable --timestamp-filename when --switch-output is provided Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 31/48] perf record: Ensure return non-zero rc when mmap fail Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 19/48] perf tools: Print write_backward value in perf_event_attr__fprintf Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 40/48] perf tools: Enable overwrite settings Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:20 +0100 [PATCH 22/48] perf tools: Add perf_data_file__switch() helper Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 25/48] perf record: Add '--timestamp-filename' option to append timestamp to output filename Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 18/48] perf tools: Only validate is_pos for tracking evsels Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 17/48] perf core: Reduce perf event output overhead by new overflow handler Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 39/48] perf tools: Detect avalibility of write_backward Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 02/48] perf tools: Adjust symbol for shared objects Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 34/48] perf tools: Automatically add new channel according to evlist Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 43/48] perf tools: Add API to pause a channel Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 04/48] perf tools: Enable BPF object configure syntax Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 44/48] perf record: Toggle overwrite ring buffer for reading Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 32/48] perf record: Prevent reading invalid data in record__mmap_read Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 21/48] perf record: Extract synthesize code to record__synthesize() Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 11/48] perf data: Support converting data from bpf_perf_event_output() Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:30 +0100 [PATCH 05/48] perf record: Apply config to BPF objects before recording Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 01/48] perf tools: Record text offset in dso to calculate objdump address Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 24/48] perf record: Introduce record__finish_output() to finish a perf.data Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 07/48] perf tools: Support setting different slots in a BPF map separately Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 47/48] perf record: Allow generate tracking events at the end of output Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 38/48] perf record: Don't poll on overwrite channel Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 48/48] perf tools: Don't warn about out of order event if write_backward is used Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 06/48] perf tools: Enable passing event to BPF object Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 42/48] perf tools: Record fd into perf_mmap Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 20/48] perf tools: Make ordered_events reusable Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 16/48] perf core: Add backward attribute to perf event Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 29/48] perf record: Re-synthesize tracking events after output switching Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 12/48] perf data: Explicitly set byte order for integer types Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100 [PATCH 03/48] perf bpf: Add API to set values to map entries in a bpf object Wang Nan <wangnan0@huawei.com> - 2016-02-22 10:40 +0100
csiph-web