Messages in this thread | | | Date | Thu, 12 Sep 2013 19:59:36 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/2] tools, perf: Add a precise event qualifier v2 |
| |
* Andi Kleen <andi@firstfloor.org> wrote:
> > Your feature to export 'precise' requirements on events looks useful to > > me. We could implement it not by special casing it implicitly but by > > saying that if ../format/precise contains something like: > > > > attr:240-241 > > > > then that's a natural extension of the config:X-Y format and should be > > interpreted to mean mean 2 bits in the perf attr field. I.e. we could go > > beyond the config bitfield. > > > > Basically the whole perf_event_attr can be thought of as a 'giant > > bitfield', in which we can specify values to export an enumerated list of > > events from the kernel to tooling. > > > > (Using attr:X-Y the config and config1 variants can be expressed as well, > > as the config fields are inside the attr structure.) > > > > The positions within the perf_attr are an ABI, so this would work pretty > > well. > > Wouldn't we need different bits for each architecture then? 32bit/64bit, > some archs with weird alignment rules, maybe different for BE/LE too? > > Ok I suppose it could be somehow auto generated in asm-offsets.c, > although I'm not sure how to get a bitfield offset there.
That, or we could indeed start adding specific field names as well, which would have a natural position and order.
Thanks,
Ingo
| |