[PATCH 0/7] xen/sched: split scheduler vtable from scheduler

Each struct scheduler currently doubles as both a scheduler 
backend's static vtable (name, opt_name, sched_id and every 
function pointer) and the per-cpupool runtime object that 
scheduler_alloc() allocates. Because these are the same type, 
scheduler_alloc() memcpy()s the entire vtable into a fresh heap 
allocation for every cpupool it creates. With N cpupools running 
the same scheduler, this duplicates N copies of identical function 
pointers and identifying fields that never differ between 
instances - the only fields that are genuinely per-cpupool are 
sched_data and cpupool.

This series splits the vtable out into its own type, struct 
sched_ops, so it can be shared by every cpupool using a given 
scheduler instead of copied per cpupool. struct scheduler is left 
holding only what is actually per-instance: a pointer to the 
shared sched_ops, plus sched_data and cpupool.

The series is structured as introduce/migrate/remove, so that 
every commit builds and boots on its own:

  - The first patch adds struct sched_ops, REGISTER_SCHED_OPS(), 
    and a sched_ops_array[] alongside the existing schedulers[], 
    extending every lookup path (scheduler_alloc(), 
    sched_get_by_name(), scheduler_init()) to search both arrays. 
    This is purely additive - no scheduler uses it yet. 

  - The next five patches each migrate one scheduler backend 
    (credit, credit2, rtds, arinc653, null) from struct scheduler 
    to struct sched_ops. Each is small, mechanical, and 
    independently bisectable, with no behavioral difference, since 
    scheduler_alloc() builds an identical runtime struct scheduler 
    regardless of which array a match is found in. 

  - The final patch removes the old schedulers[] and 
    REGISTER_SCHEDULER() path now that nothing uses it, shrinks 
    struct scheduler down to { ops, sched_data, cpupool }, and 
    updates every accessor in private.h accordingly.

Furkan Caliskan (7):
  xen/sched: introduce struct sched_ops as a shared scheduler vtable
  xen/sched: credit: migrate to new sched_ops
  xen/sched: credit2: migrate to new sched_ops
  xen/sched: rtds: migrate to new sched_ops
  xen/sched: arinc653: migrate to new sched_ops
  xen/sched: null: migrate to new sched_ops
  xen/sched: remove old scheduler registration, shrink struct scheduler

 xen/arch/arm/xen.lds.S      |   2 +-
 xen/arch/ppc/xen.lds.S      |   2 +-
 xen/arch/riscv/xen.lds.S    |   2 +-
 xen/arch/x86/xen.lds.S      |   2 +-
 xen/common/sched/arinc653.c |  11 +---
 xen/common/sched/core.c     |  80 ++++++++++++++++-------------
 xen/common/sched/cpupool.c  |   6 +--
 xen/common/sched/credit.c   |   5 +-
 xen/common/sched/credit2.c  |   5 +-
 xen/common/sched/null.c     |   5 +-
 xen/common/sched/private.h  | 100 +++++++++++++++++++-----------------
 xen/common/sched/rt.c       |   5 +-
 xen/include/xen/xen.lds.h   |   8 +--
 13 files changed, 116 insertions(+), 117 deletions(-)

-- 
2.34.1