Messages in this thread | | | Date | Wed, 12 Feb 2020 13:08:15 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH RFC 4/7] perf pmu: Rename uncore symbols to include system PMUs |
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On Tue, Feb 11, 2020 at 03:36:39PM +0000, John Garry wrote: > On 11/02/2020 14:43, Jiri Olsa wrote: > > > root@(none)$ pwd > > > /sys/bus/event_source/devices/smmuv3_pmcg_100020 > > > root@(none)$ ls -l > > > total 0 > > > -r--r--r-- 1 root root 4096 Feb 10 14:50 cpumask > > > drwxr-xr-x 2 root root 0 Feb 10 14:50 events > > > drwxr-xr-x 2 root root 0 Feb 10 14:50 format > > > -rw-r--r-- 1 root root 4096 Feb 10 14:50 > > > perf_event_mux_interval_ms > > > drwxr-xr-x 2 root root 0 Feb 10 14:50 power > > > lrwxrwxrwx 1 root root 0 Feb 10 14:50 subsystem -> > > > ../../bus/event_source > > > -r--r--r-- 1 root root 4096 Feb 10 14:50 type > > > -rw-r--r-- 1 root root 4096 Feb 10 14:50 uevent > > > > > > > > > Other PMU drivers which I have checked in drivers/perf also have the same. > > > > > > Indeed I see no way to differentiate whether a PMU is an uncore or system. > > > So that is why I change the name to cover both. Maybe there is a better name > > > than the verbose pmu_is_uncore_or_sys(). > > > > > > > I don't see the connection here with the sysid or '_sys' checking, > > > > that's just telling which ID to use when looking for an alias, no? > > > So the connection is that in perf_pmu__find_map(), for a given PMU, the > > > matching is now extended from only core or uncore PMUs to also these system > > > PMUs. And I use the sysid to find an aliasing table for any system PMUs > > > present. > > Hi Jirka, > > > I see.. can't we just check sysid for uncore PMUs? > > x86 will still alias PMUs (uncore or CPU) based on an alias table matched to > the cpuid, as it is today. x86 has the benefit of fixed uncore PMUs for a > given cpuid.
ok, I did mean 'on addition' to the cpuid checks
> > For other archs whose uncore or system PMUs are not fixed for a given CPU - > like arm - we will support matching uncore and system PMUs on cpuid or > sysid. > > Uncore PMUs are a grey area for arm, as they may or may not be tied to a > specific cpuid, so we will need to support both matching methods. > > because > > that's what the code is doing, right? > > Not exactly. > > The code will match on an alias table matched to the cpuid and also an alias > table matched to the sysid (if perf could actually get a sysid and there is > a table matching that sysid). > > I hope that this makes sense....
right, please make sure this kind of explanation is in changelog or better in the code comment
thanks, jirka
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