On Wed 25-01-23 04:34:57, Leonardo Bras wrote: > Disclaimer: > a - The cover letter got bigger than expected, so I had to split it in > sections to better organize myself. I am not very confortable with it. > b - Performance numbers below did not include patch 5/5 (Remove flags > from memcg_stock_pcp), which could further improve performance for > drain_all_stock(), but I could only notice the optimization at the > last minute. > > > 0 - Motivation: > On current codebase, when drain_all_stock() is ran, it will schedule a > drain_local_stock() for each cpu that has a percpu stock associated with a > descendant of a given root_memcg. > > This happens even on 'isolated cpus', a feature commonly used on workloads that > are sensitive to interruption and context switching such as vRAN and Industrial > Control Systems. > > Since this scheduling behavior is a problem to those workloads, the proposal is > to replace the current local_lock + schedule_work_on() solution with a per-cpu > spinlock. If IIRC we have also discussed that isolated CPUs can simply opt out from the pcp caching and therefore the problem would be avoided altogether without changes to the locking scheme. I do not see anything regarding that in this submission. Could you elaborate why you have abandoned this option? -- Michal Hocko SUSE Labs
