[PATCH v4 0/3] sched: make migrate_enable/migrate_disable inline

[Menglong Dong <menglong.dong@linux.dev>]

In this series, we make migrate_enable/migrate_disable inline to obtain
better performance in some case.

In the first patch, we add the macro "COMPILE_OFFSETS" to all the
asm-offset.c to avoid circular dependency in the 2nd patch.

In the 2nd patch, we generate the offset of nr_pinned in "struct rq" with
rq-offsets.c, as the "struct rq" is defined internally and we need to
access the "nr_pinned" field in migrate_enable and migrate_disable. Then,
we move the definition of migrate_enable/migrate_disable from
kernel/sched/core.c to include/linux/sched.h.

In the 3rd patch, we fix some typos in include/linux/preempt.h.

One of the beneficiaries of this series is BPF trampoline. Without this
series, the migrate_enable/migrate_disable is hot when we run the
benchmark for FENTRY, FEXIT, MODIFY_RETURN, etc:

  54.63% bpf_prog_2dcccf652aac1793_bench_trigger_fentry [k]
                 bpf_prog_2dcccf652aac1793_bench_trigger_fentry
  10.43% [kernel] [k] migrate_enable
  10.07% bpf_trampoline_6442517037 [k] bpf_trampoline_6442517037
  8.06% [kernel] [k] __bpf_prog_exit_recur
  4.11% libc.so.6 [.] syscall
  2.15% [kernel] [k] entry_SYSCALL_64
  1.48% [kernel] [k] memchr_inv
  1.32% [kernel] [k] fput
  1.16% [kernel] [k] _copy_to_user
  0.73% [kernel] [k] bpf_prog_test_run_raw_tp

Before this patch, the performance of BPF FENTRY is:

  fentry         :  113.030 ± 0.149M/s
  fentry         :  112.501 ± 0.187M/s
  fentry         :  112.828 ± 0.267M/s
  fentry         :  115.287 ± 0.241M/s

After this patch, the performance of BPF FENTRY increases to:

  fentry         :  143.644 ± 0.670M/s
  fentry         :  149.764 ± 0.362M/s
  fentry         :  149.642 ± 0.156M/s
  fentry         :  145.263 ± 0.221M/s

Changes since V3:
* some modification on the 2nd patch, as Alexei advised:
 - rename CREATE_MIGRATE_DISABLE to INSTANTIATE_EXPORTED_MIGRATE_DISABLE
 - add document for INSTANTIATE_EXPORTED_MIGRATE_DISABLE

Changes since V2:
* some modification on the 2nd patch, as Peter advised:
  - don't export runqueues, define migrate_enable and migrate_disable in
    kernel/sched/core.c and use them for kernel modules instead
  - define the macro this_rq_pinned()
  - add some comment for this_rq_raw()

Changes since V1:
* use PERCPU_PTR() for this_rq_raw() if !CONFIG_SMP in the 2nd patch

Menglong Dong (3):
  arch: add the macro COMPILE_OFFSETS to all the asm-offsets.c
  sched: make migrate_enable/migrate_disable inline
  sched: fix some typos in include/linux/preempt.h

 Kbuild                               |  13 ++-
 arch/alpha/kernel/asm-offsets.c      |   1 +
 arch/arc/kernel/asm-offsets.c        |   1 +
 arch/arm/kernel/asm-offsets.c        |   2 +
 arch/arm64/kernel/asm-offsets.c      |   1 +
 arch/csky/kernel/asm-offsets.c       |   1 +
 arch/hexagon/kernel/asm-offsets.c    |   1 +
 arch/loongarch/kernel/asm-offsets.c  |   2 +
 arch/m68k/kernel/asm-offsets.c       |   1 +
 arch/microblaze/kernel/asm-offsets.c |   1 +
 arch/mips/kernel/asm-offsets.c       |   2 +
 arch/nios2/kernel/asm-offsets.c      |   1 +
 arch/openrisc/kernel/asm-offsets.c   |   1 +
 arch/parisc/kernel/asm-offsets.c     |   1 +
 arch/powerpc/kernel/asm-offsets.c    |   1 +
 arch/riscv/kernel/asm-offsets.c      |   1 +
 arch/s390/kernel/asm-offsets.c       |   1 +
 arch/sh/kernel/asm-offsets.c         |   1 +
 arch/sparc/kernel/asm-offsets.c      |   1 +
 arch/um/kernel/asm-offsets.c         |   2 +
 arch/xtensa/kernel/asm-offsets.c     |   1 +
 include/linux/preempt.h              |  11 +--
 include/linux/sched.h                | 113 +++++++++++++++++++++++++++
 kernel/bpf/verifier.c                |   1 +
 kernel/sched/core.c                  |  63 ++++-----------
 kernel/sched/rq-offsets.c            |  12 +++
 26 files changed, 180 insertions(+), 57 deletions(-)
 create mode 100644 kernel/sched/rq-offsets.c

-- 
2.51.0