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"? -- Best Regards, Huang, Ying
