On 06/29/2011 07:08 PM, Frederic Weisbecker wrote:
On Wed, Jun 29, 2011 at 06:42:35PM +0300, Avi Kivity wrote:
> The perf_event overflow handler does not receive any caller-derived
> argument, so many callers need to resort to looking up the perf_event
> in their local data structure. This is ugly and doesn't scale if a
> single callback services many perf_events.
>
> Fix by adding a context parameter to perf_event_create_kernel_counter()
> (and derived hardware breakpoints APIs) and storing it in the perf_event.
> The field can be accessed from the callback as
event->overflow_handler_context.
> All callers are updated.
>
> Signed-off-by: Avi Kivity<[email protected]>
I believe it can micro-optimize ptrace through register_user_hw_breakpoint()
because
we could store the index of the breakpoint that way, instead of iterating
through 4 slots.
Right, I noticed that while writing the patch.
Perhaps it can help in arm too, adding Will in Cc.
But for register_wide_hw_breakpoint, I'm not sure. kgdb is the main user, may
be Jason
could find some use of it.
I think an API should not require its users to iterate in their
callbacks, even if it doesn't affect current users for some reason.
--
error compiling committee.c: too many arguments to function
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