Peter Zijlstra <[email protected]> writes: > On Wed, Jun 11, 2014 at 06:41:45PM +0300, Alexander Shishkin wrote: >> + /* >> + * Set up pmu-private data structures for an AUX area >> + */ >> + void *(*setup_aux) (int cpu, void **pages, >> + int nr_pages, bool overwrite); >> + /* optional */ >> + >> + /* >> + * Free pmu-private AUX data structures >> + */ >> + void (*free_aux) (void *aux); /* optional */ > > I was hoping you could replace those with a PERF_CAP_AUX or something > and then have one generic allocation routine like you provide in the > subsequent patches.
I need these to allocate pmu-specific SG tables now, which I don't see how to generalize nicely. User-visible aux_pages are allocated in the generic rb_alloc_aux(). As for sg tables, the alternative would be to allocate them in the event::pmu::add() path, which is probably not very good for performance, unless I'm missing something? Like, I can allocate stuff in the first add() and then free it in event::destroy(). Or, we can assume a generic sg table format and allocate them in the generic code, but then we'll need more capabilities to indicate at least the size of a table entry. PT needs 64 bits per entry, ARM's TMC needs 32 and the non-SG PT will still need some tables. But I'd rather leave this part to the pmu drivers. What do you think? Regards, -- Alex -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
