On Thu, Jul 11, 2024 at 2:44 PM Huang, Ying <ying.huang@xxxxxxxxx> wrote: > > Yafang Shao <laoar.shao@xxxxxxxxx> writes: > > > On Wed, Jul 10, 2024 at 10:51 AM Huang, Ying <ying.huang@xxxxxxxxx> wrote: > >> > >> Yafang Shao <laoar.shao@xxxxxxxxx> writes: > >> > >> > The configuration parameter PCP_BATCH_SCALE_MAX poses challenges for > >> > quickly experimenting with specific workloads in a production environment, > >> > particularly when monitoring latency spikes caused by contention on the > >> > zone->lock. To address this, a new sysctl parameter vm.pcp_batch_scale_max > >> > is introduced as a more practical alternative. > >> > >> In general, I'm neutral to the change. I can understand that kernel > >> configuration isn't as flexible as sysctl knob. But, sysctl knob is ABI > >> too. > >> > >> > To ultimately mitigate the zone->lock contention issue, several suggestions > >> > have been proposed. One approach involves dividing large zones into multi > >> > smaller zones, as suggested by Matthew[0], while another entails splitting > >> > the zone->lock using a mechanism similar to memory arenas and shifting away > >> > from relying solely on zone_id to identify the range of free lists a > >> > particular page belongs to[1]. However, implementing these solutions is > >> > likely to necessitate a more extended development effort. > >> > >> Per my understanding, the change will hurt instead of improve zone->lock > >> contention. Instead, it will reduce page allocation/freeing latency. > > > > I'm quite perplexed by your recent comment. You introduced a > > configuration that has proven to be difficult to use, and you have > > been resistant to suggestions for modifying it to a more user-friendly > > and practical tuning approach. May I inquire about the rationale > > behind introducing this configuration in the beginning? > > Sorry, I don't understand your words. Do you need me to explain what is > "neutral"? No, thanks. After consulting with ChatGPT, I received a clear and comprehensive explanation of what "neutral" means, providing me with a better understanding of the concept. So, can you explain why you introduced it as a config in the beginning ? -- Regards Yafang
