From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 1/2] tools, perf: Add a precise event qualifier v2 Date: Thu, 12 Sep 2013 19:36:17 +0200 Message-ID: <20130912173617.GI18242@two.firstfloor.org> References: <1374501138-13496-1-git-send-email-andi@firstfloor.org> <20130723060108.GA18396@tassilo.jf.intel.com> <20130723225150.GT6123@two.firstfloor.org> <20130912165733.GA23698@gmail.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20130912165733.GA23698@gmail.com> Sender: trinity-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ingo Molnar Cc: Andi Kleen , Vince Weaver , Andi Kleen , acme@infradead.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Stephane Eranian , torvalds@linux-foundation.org, trinity@vger.kernel.org, Peter Zijlstra , Thomas Gleixner , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Jiri Olsa , Namhyung Kim > 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. -Andi -- ak@linux.intel.com -- Speaking for myself only.