From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 27 Jan 2012 17:10:09 +0000 Subject: oprofile and ARM A9 hardware counter In-Reply-To: References: <20120127121311.GB2347@mudshark.cambridge.arm.com> <20120127132826.GD2347@mudshark.cambridge.arm.com> <20120127155454.GH2347@mudshark.cambridge.arm.com> <20120127165941.GK2347@mudshark.cambridge.arm.com> Message-ID: <20120127171009.GL2347@mudshark.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Jan 27, 2012 at 05:03:28PM +0000, stephane eranian wrote: > On Fri, Jan 27, 2012 at 5:59 PM, Will Deacon wrote: > > That said, if you see any bugs in the code please do shout! > > > I suspect there is something wrong, we shouldn't hit the max_rate_limit. > You may have bursts of interrupts (samples). I'll check on that this week-end. Ok, thanks. Keep in mind that you probably have variable rate clocks, which will affect the cycle counter frequency. > >> > A7 and A15 have the ability to filter counters based on privilege level, so > >> > you can get more accurate userspace counts there. > >> > >> Ok, that's better. Need to update libpfm4 for A15 with priv levels then! > > > > How do you handle that in libpfm4? On ARM, the event encodings remain the same, > > you just need to set some extra bits to determine which levels are included or > > excluded (you can do this with the perf tool by using the :{u,k,h} suffix on an > > event description). > > > It depends what you call the encoding? If the priv level can be encoded in the > attr->config field, then that's easy. If it needs to be set somewhere else, then > we need to figure out how you encode it in the attr struct. Either in some other > bits in attr->config or use attr->config1, for instance. You tell me. The way it's done with perf is to set the exclude{user,kernel,hv} fields in the attr. The ARM perf backend then translates these into the relevant bits which get orred into the config_base before hitting the hardware. Will