powerpc: Add preempt lazy support

Define preempt lazy bit for Powerpc. Use bit 9 which is free and within
16 bit range of NEED_RESCHED, so compiler can issue single andi.

Since Powerpc doesn't use the generic entry/exit, add lazy check at exit
to user. CONFIG_PREEMPTION is defined for lazy/full/rt so use it for
return to kernel.

Ran a few benchmarks and db workload on Power10. Performance is close to
preempt=none/voluntary.

Since Powerpc systems can have large core count and large memory,
preempt lazy is going to be helpful in avoiding soft lockup issues.

Reviewed-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Ankur Arora <[email protected]>
Signed-off-by: Shrikanth Hegde <[email protected]>
Signed-off-by: Madhavan Srinivasan <[email protected]>
Link: https://patch.msgid.link/[email protected]

0 files changed, 0 insertions, 0 deletions