[PATCH v9 07/10] arm: arm64: pmu: Assign platform PMU CPU affinity
From: Jeremy Linton <hidden>
Date: 2016-09-16 15:35:32
Also in:
linux-acpi
Hi Thanks for taking a look at this.. On 09/16/2016 08:29 AM, Will Deacon wrote:
On Wed, Sep 14, 2016 at 05:32:35PM -0500, Jeremy Linton wrote:quoted
On systems with multiple PMU types the PMU to CPU affinity needs to be detected and set. The CPU to interrupt affinity should also be set.
(trimming)
quoted
continue; ret = info->init(pmu); + /* + * if this pmu declaration is unspecified and we have + * previously found a PMU on this platform then append + * a PMU number to the pmu name. This avoids changing + * the names of PMUs that are specific to a class of CPUs. + * The assumption is that if we match a specific PMU in the + * provided pmu_probe_info then it's unique, and another PMU + * in the system will match a different entry rather than + * needing the _number to assure its unique. + */ + if ((!info->cpuid) && (duplicate_pmus)) {Hmm, the duplicate_pmus check looks a little odd here. Doesn't it mean that you'd end up with things like: "arm,armv8-pmuv3" "arm,armv8-pmuv3_1" which looks needlessly fiddly to parse. Is this intentional?
Well, IIRC, you recommend that format, or maybe I misunderstood. Anyway, per the comment I'm trying to assure that legacy platform devices don't accidentally get a "_X" appended to their name and break something. Further, by itself the name itself doesn't have any meaning/ordering and could just as well be a random string. So, I don't think anyone is going to try and parse it except to compare it as a whole something like "armv8_cortex_a53". Which is why the cpu affinity is required. Additionally, doing it this way allows a tiny tweak to the pmu table in the future to re-enable meaningful PMU names. Lastly, its big.little exclusive, so I would rather apply pain to non-existant big.little server machines, than uglify the common case.