From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Date: Mon, 27 Sep 2010 22:26:27 +0000 Subject: Re: [PATCH 6/6] sh: oprofile: Use perf-events oprofile backend Message-Id: <20100927222627.GH28588@console-pimps.org> List-Id: References: <20100916143254.GC13563@erda.amd.com> <20100927200138.GG28588@console-pimps.org> <20100927220703.GV13563@erda.amd.com> In-Reply-To: <20100927220703.GV13563@erda.amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Robert Richter Cc: Will Deacon , Paul Mundt , Russell King , "linux-arm-kernel@lists.infradead.org" , "linux-sh@vger.kernel.org" , Peter Zijlstra , Ingo Molnar , Frederic Weisbecker , Arnaldo Carvalho de Melo , "linux-arch@vger.kernel.org" On Tue, Sep 28, 2010 at 12:07:03AM +0200, Robert Richter wrote: > On 27.09.10 16:01:38, Matt Fleming wrote: > > On Thu, Sep 16, 2010 at 04:32:54PM +0200, Robert Richter wrote: > > > > diff --git a/arch/sh/kernel/perf_event.c b/arch/sh/kernel/perf_event.c > > > > index 2cb9ad5..3c3fc9a 100644 > > > > --- a/arch/sh/kernel/perf_event.c > > > > +++ b/arch/sh/kernel/perf_event.c > > > > @@ -59,6 +59,14 @@ static inline int sh_pmu_initialized(void) > > > > return !!sh_pmu; > > > > } > > > > > > > > +const char *sh_pmu_name(void) > > > > +{ > > > > + if (!sh_pmu) > > > > + return NULL; > > > > + > > > > + return sh_pmu->name; > > > > +} > > > > > > Couldn't we make this a generic function like perf_num_counters()? > > > > Well, ARM doesn't have names as strings for its pmus currently. What's > > more, ARM wouldn't use it; SH would be the only user of this function. I > > don't think this one makes sense to be a generic function. > > I didn't catch this with my first review, the function will need an > EXPORT_SYMBOL_GPL() to allow building modules. This will mean an > interface extension what should be non-arch. So, for architectures we > need the pmu name like SH we just implement the generic function. For > ARM we don't need to provide this function. Yeah my bad, I just hit this EXPORT_SYMBOL_GPL issue when compiling oprofile as a module. > Most of the interface is defined in linux/perf_event.h. We shouldn't > move this to asm/perf_event.h, so this is one more argument for the > non-arch implementation. I'm not advocating moving this function to asm/perf_event.h. > As the implementation of the function would be optional, why should we > make it architectural? I don't see why we should pollute the perf namespace with a function that is only being used inside the SH oprofile code? There would be exactly one use of this function and I doubt the perf guys will want this function exposed. In it's current state, it really is no use to any architecture other than SH. We can always add a generic perf_pmu_name() function later if needed, but it's definitely not needed at the moment.