Commit-ID: ae0c2d995d648d5165545d5e05e2869642009b38
Gitweb: http://git.kernel.org/tip/ae0c2d995d648d5165545d5e05e2869642009b38
Author: Alexander Shishkin <[email protected]>
AuthorDate: Mon, 20 Feb 2017 15:33:51 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 16 Mar 2017 09:51:11 +0100
perf/core: Add a flag for partial AUX records
The Intel PT driver needs to be able to communicate partial AUX transactions,
that is, transactions with gaps in data for reasons other than no room
left in the buffer (i.e. truncated transactions). Therefore, this condition
does not imply a wakeup for the consumer.
To this end, add a new "partial" AUX flag.
Signed-off-by: Alexander Shishkin <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mathieu Poirier <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
include/uapi/linux/perf_event.h | 1 +
kernel/events/ring_buffer.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
index bec0aad..d09a9cd 100644
--- a/include/uapi/linux/perf_event.h
+++ b/include/uapi/linux/perf_event.h
@@ -915,6 +915,7 @@ enum perf_callchain_context {
*/
#define PERF_AUX_FLAG_TRUNCATED 0x01 /* record was truncated to fit */
#define PERF_AUX_FLAG_OVERWRITE 0x02 /* snapshot from overwrite mode */
+#define PERF_AUX_FLAG_PARTIAL 0x04 /* record contains gaps */
#define PERF_FLAG_FD_NO_GROUP (1UL << 0)
#define PERF_FLAG_FD_OUTPUT (1UL << 1)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 9654e55..2831480 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -424,8 +424,8 @@ err:
*/
void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
{
+ bool wakeup = !!(handle->aux_flags & PERF_AUX_FLAG_TRUNCATED);
struct ring_buffer *rb = handle->rb;
- bool wakeup = !!handle->aux_flags;
unsigned long aux_head;
/* in overwrite mode, driver provides aux_head via handle */
On Thu, 16 Mar 2017, tip-bot for Alexander Shishkin wrote:
> Commit-ID: ae0c2d995d648d5165545d5e05e2869642009b38
> perf/core: Add a flag for partial AUX records
>
> The Intel PT driver needs to be able to communicate partial AUX transactions,
> that is, transactions with gaps in data for reasons other than no room
> left in the buffer (i.e. truncated transactions). Therefore, this condition
> does not imply a wakeup for the consumer.
>
> To this end, add a new "partial" AUX flag.
...
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index bec0aad..d09a9cd 100644
> --- a/include/uapi/linux/perf_event.h
> +++ b/include/uapi/linux/perf_event.h
> @@ -915,6 +915,7 @@ enum perf_callchain_context {
> */
> #define PERF_AUX_FLAG_TRUNCATED 0x01 /* record was truncated to fit */
> #define PERF_AUX_FLAG_OVERWRITE 0x02 /* snapshot from overwrite mode */
> +#define PERF_AUX_FLAG_PARTIAL 0x04 /* record contains gaps */
was this included in the wrong patch? It adds the flag but nothing uses
it? Though it appears a later patch makes use of it.
This makes it confusing when trying to update the perf_event_open.2
manpage, as the git commit that adds the new ABI to perf_event.h doesn't
seem to have anything to do with any behavior affected by it.
> #define PERF_FLAG_FD_NO_GROUP (1UL << 0)
> #define PERF_FLAG_FD_OUTPUT (1UL << 1)
> diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
> index 9654e55..2831480 100644
> --- a/kernel/events/ring_buffer.c
> +++ b/kernel/events/ring_buffer.c
> @@ -424,8 +424,8 @@ err:
> */
> void perf_aux_output_end(struct perf_output_handle *handle, unsigned long size)
> {
> + bool wakeup = !!(handle->aux_flags & PERF_AUX_FLAG_TRUNCATED);
> struct ring_buffer *rb = handle->rb;
> - bool wakeup = !!handle->aux_flags;
> unsigned long aux_head;
>