This is an attempt at providing clearer names as discussed here:
https://github.com/linuxppc/issues/issues/164
as well as providing better behavior for RTAS_BUSY (-2) and small
extended delay values, which in my experience seem more common than
the larger ones. In testing PREEMPT_NONE kernels with CPUs busy, I see
the elapsed time for memory add operations roughly halved, while
memory remove operations' elapsed time shrinks by about ~25%. This is
achieved without significantly more time spent on CPU:
(- is before, + is after)
Performance counter stats for 'drmgr -c mem -a -q 10' (10 runs):
- 1,898 probe:rtas_call # 0.003 M/sec
( +- 2.20% )
- 751.57 msec task-clock # 0.289 CPUs utilized
( +- 1.56% )
+ 1,969 probe:rtas_call # 0.003 M/sec
( +- 2.69% )
+ 766.20 msec task-clock # 0.688 CPUs utilized
( +- 1.99% )
- 2.605 +- 0.148 seconds time elapsed ( +- 5.70% )
+ 1.1129 +- 0.0660 seconds time elapsed ( +- 5.93% )
Performance counter stats for 'drmgr -c mem -r -q 10' (10 runs):
- 673 probe:rtas_call # 0.002 M/sec
( +- 0.55% )
- 318.36 msec task-clock # 0.234 CPUs utilized
( +- 0.42% )
+ 692 probe:rtas_call # 0.002 M/sec
( +- 0.73% )
+ 320.87 msec task-clock # 0.309 CPUs utilized
( +- 0.34% )
- 1.362 +- 0.100 seconds time elapsed ( +- 7.37% )
+ 1.0372 +- 0.0468 seconds time elapsed ( +- 4.51% )
Questions / concerns / to do:
* I don't love the new API function names.
* Introduces three new APIs when two likely would suffice.
* Need to convert eeh_pseries and scanlog.
* rtas_busy_delay() and rtas_busy_delay_time() not yet removed.
Nathan Lynch (10):
powerpc/rtas: new APIs for busy and extended delay statuses
powerpc/rtas: do not schedule in rtas_os_term()
powerpc/rtas-rtc: convert get-time-of-day to rtas_force_spin_if_busy()
powerpc/rtas-rtc: convert set-time-of-day to rtas_sched_if_busy()
powerpc/pseries/fadump: convert to rtas_sched_if_busy()
powerpc/pseries/msi: convert to rtas_sched_if_busy()
powerpc/pseries/iommu: convert to rtas_sched_if_busy()
powerpc/pseries/dlpar: convert to rtas_sched_if_busy()
powerpc/rtas: convert to rtas_sched_if_busy()
powerpc/rtas_flash: convert to rtas_sched_if_busy()
arch/powerpc/include/asm/rtas.h | 4 +
arch/powerpc/kernel/rtas-rtc.c | 38 +---
arch/powerpc/kernel/rtas.c | 178 ++++++++++++++++++-
arch/powerpc/kernel/rtas_flash.c | 4 +-
arch/powerpc/platforms/pseries/dlpar.c | 2 +-
arch/powerpc/platforms/pseries/iommu.c | 2 +-
arch/powerpc/platforms/pseries/msi.c | 4 +-
arch/powerpc/platforms/pseries/rtas-fadump.c | 22 +--
8 files changed, 190 insertions(+), 64 deletions(-)
--
2.30.2
