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SubjectRe: [PATCH 3/6] perf_counter: per event wakeups

* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> By request, provide a way to request a wakeup every 'n' events instead
> of every page of output.
>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> ---
> include/linux/perf_counter.h | 3 ++-
> kernel/perf_counter.c | 10 +++++++++-
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/include/linux/perf_counter.h
> ===================================================================
> --- linux-2.6.orig/include/linux/perf_counter.h
> +++ linux-2.6/include/linux/perf_counter.h
> @@ -146,7 +146,7 @@ struct perf_counter_hw_event {
> __reserved_1 : 52;
>
> __u32 extra_config_len;
> - __u32 __reserved_4;
> + __u32 wakeup_events; /* wakeup every n events */

[ Sidenote: i think we need more reserved bits :-) Expand the ABI
while it's still easy ;-) ]

I have a design observation here:

i think 'wakeup' is a user-space notification type. Another type of
notication can be 'signal', or 'none'.

Perhaps your current scheme makes the most sense: to treat them as
separate attributes, and allow signal delivery and wakeups at once.
(if user-space so wishes)

Agreed?

Ingo


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