Messages in this thread | | | Subject | Re: [PATCH 4/4][RFC] perf_counter: Allow sharing of output channels | From | Peter Zijlstra <> | Date | Wed, 19 Aug 2009 13:07:37 +0200 |
| |
On Wed, 2009-08-19 at 12:58 +0200, Ingo Molnar wrote: > * Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > > > Provide the ability to configure a counter to send its output to > > another (already existing) counter's output stream. > > > > [ compile tested only ] > > very nice! > > two comments: > > > 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 > > @@ -216,6 +216,7 @@ struct perf_counter_attr { > > #define PERF_COUNTER_IOC_REFRESH _IO ('$', 2) > > #define PERF_COUNTER_IOC_RESET _IO ('$', 3) > > #define PERF_COUNTER_IOC_PERIOD _IOW('$', 4, u64) > > +#define PERF_COUNTER_IOC_SET_OUTPUT _IO ('$', 5) > > Time to add a new sys_perf_counter_chattr() syscall and deprecate > the ioctls?
Could do I guess.. in order to support things like refresh and reset we need a few new offset fields in the attr struct, but that's doable.
> > @@ -415,6 +416,9 @@ enum perf_callchain_context { > > PERF_CONTEXT_MAX = (__u64)-4095, > > }; > > > > +#define PERF_FLAG_FD_NO_GROUP (1U << 0) > > +#define PERF_FLAG_FD_OUTPUT (1U << 1) > > Why not extend the size of perf_counter_attr and add an output_fd > parameter? Zero would mean no fd (and this is also backwards > compatible behavior). > > FD_NO_GROUP is a bit unclean API as it aliases group_fd to two > purposes: the real group_fd and this new output_fd. I think we > should move output_fd to the attribute structure.
Yeah, the NO_GROUP thing is ugly..
I'll wait for some more comments before reworking this.
| |