perf: remove __weak function hw_perf_group_sched_in()

From the discussion of thread "[RFC] perf_events: support for uncore

One thing not on that list, which should happen first I guess, is to remove hw_perf_group_sched_in(). The idea is to add some sort of transactional API to the struct pmu, so that we can delay the schedulability check until commit time (and roll back when it fails).

Something as simple as:

 struct pmu {
   void start_txn(struct pmu *);
   void commit_txn(struct pmu *);

   ,,,

};

and then change group_sched_in() to use this instead of hw_perf_group_sched_in(), whose implementations mostly replicate group_sched_in() in various buggy ways anyway.

This patch series is to remove hw_perf_group_sched_in() first.

patch 1: core, add group scheduling transactional APIs patch 2: x86, implement group scheduling transactional APIs patch 3: powerpc, implement group scheduling transactional APIs patch 4: sparc, implement group scheduling transactional APIs

Thanks for any comment.

Quoted 7 lines · Lin Ming

This patch series is to remove hw_perf_group_sched_in() first.

patch 1: core, add group scheduling transactional APIs patch 2: x86, implement group scheduling transactional APIs patch 3: powerpc, implement group scheduling transactional APIs patch 4: sparc, implement group scheduling transactional APIs

Quoted 1 line

Thanks for any comment.

Don't RISC architectures deal better with word sized variables than with u8? I thought it curious you used u8 for the flags thing instead of int or long, but I'm not quite sure it really matters one way or the other.