Re: [PATCH 1/4 fix] perf core: Introduce new ioctl options to pause and resume ring buffer

Alexei Starovoitov
2016-03-29T04:39:48Z

On Tue, Mar 29, 2016 at 02:05:07AM +0000, Wang Nan wrote:
> Add new ioctl() to pause/resume ring-buffer output.
>
> In some situations we want to read from ring buffer only when we
> ensure nothing can write to the ring buffer during reading. Without
> this patch we have to turn off all events attached to this ring buffer
> to achieve this.
>
> This patch is for supporting overwrite ring buffer. Following
> commits will introduce new methods support reading from overwrite ring
> buffer. Before reading, caller must ensure the ring buffer is frozen, or
> the reading is unreliable.
>
> 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/uapi/linux/perf_event.h | 1 +
> kernel/events/core.c | 13 +++++++++++++
> kernel/events/internal.h | 11 +++++++++++
> kernel/events/ring_buffer.c | 7 ++++++-
> 4 files changed, 31 insertions(+), 1 deletion(-)

Acked-by: Alexei Starovoitov <ast@kernel.org>