Messages in this thread | | | Date | Thu, 20 Apr 2017 09:53:00 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH 3/3] perf tool, arm64, thunderx2: Add implementation defined events for ThunderX2 |
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On Wed, Apr 19, 2017 at 11:37:31PM +0530, Ganapatrao Kulkarni wrote: > Hi Mark,
Hi,
> On Thu, Apr 6, 2017 at 3:25 PM, Mark Rutland <mark.rutland@arm.com> wrote: > > On Thu, Apr 06, 2017 at 09:50:33AM +0530, Ganapatrao Kulkarni wrote: > >> On Wed, Apr 5, 2017 at 3:35 PM, Mark Rutland <mark.rutland@arm.com> wrote: > >> > On Wed, Apr 05, 2017 at 02:42:39PM +0530, Ganapatrao Kulkarni wrote: > >> >> On Tue, Apr 4, 2017 at 5:58 PM, Mark Rutland <mark.rutland@arm.com> wrote: > >> >> > On Tue, Apr 04, 2017 at 01:06:43PM +0530, Ganapatrao Kulkarni wrote: > > > >> >> >> + "CPU" :"armv8_pmuv3_0" > >> >> > > >> >> > Please let's not hard-code the name like this. Surely we can get rid of this? > >> >> > > >> >> > The kernel doesn't currently name PMUs as armv8_pmuv3_*, and as that can > >> >> > differ across DT/ACPI and in big.LITTLE, I don't think it makes sense to > >> >> > try to rely one particular string regardless. > >> >> > >> >> This string/name is fixed for a platform. having name here is essential to > >> >> know which devices among pmu (armv8_pmuv3_0, breakpoint, software) > >> >> devices, these jevents to be added. > >> >> also this json file is specific to a arch/soc/board, it is not a > >> >> generic file to be common. > >> > > >> > This file describe the events of a CPU PMU, and CPUs are not specific to > >> > a platform in general. There are many systems using Cortex-A57, for > >> > example. > >> > > >> > Across big.LITTLE SoCs with Cortex-A57, there's no guarantee as to > >> > whether the Cortex-A57 cores would be named armv8_pmuv3_0, or > >> > armv8_pmuv3_1, etc. This would depend on the boot CPU, probe order of > >> > secondaries, etc. > > some of the applications(perf etc) use sysfs files of perf PMU CORE devices. > at present the names are created as per SOC/platform like > armv8_pmuv3, armv8_cavium_thunder, armv8_cortex_a57 etc. > > cpu_pmu->name = "armv8_cavium_thunder"; > > can we please have common name similar to x86(cpu) and call them as > cpu_0 and cpu_1?
I don't see how that helps in this case?
I'd rather that we expose some mechanism to determine whether a PMU is a CPU PMU, other than the name. Userspace can then throw away the name if it so wishes, and it doesn't have the potential to break existing users.
Thanks, Mark.
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