Messages in this thread | | | Date | Wed, 29 Jun 2011 19:25:58 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH 1/3] perf: add context field to perf_event |
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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<avi@redhat.com> > > 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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