Shrikanth Hegde <sshe...@linux.ibm.com> writes: > Thank you Sebastian for taking a look and rwb tag. > >> On 2024-11-08 15:48:53 [+0530], Shrikanth Hegde wrote: >>> 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. It is possible that some patterns would >>> differ in lazy[2]. More details of preempt lazy is here [1] >>> >>> Since Powerpc system can have large core count and large memory, >>> preempt lazy is going to be helpful in avoiding soft lockup issues. >>> >>> [1]: https://lore.kernel.org/lkml/20241007074609.447006...@infradead.org/ >>> [2]: >>> https://lore.kernel.org/all/1a973dda-c79e-4d95-935b-e4b93eb07...@linux.ibm.com/ >> >> The lazy bits are only in tip. > > Hi Michael, I sent it to powerpc tree since all the changes were in > arch/powerpc. Please let me know if i have send it to tip tree instead.
I think I'd like it to have a full cycle of testing in next before going into mainline. So I'll plan to take this via the powerpc tree for the next cycle. I assume you haven't tested 32-bit at all? cheers
