On 11/1/2024 4:50 PM, Michal Hocko wrote: > On Fri 01-11-24 16:39:07, Stepanov Anatoly wrote: >> On 11/1/2024 4:28 PM, Michal Hocko wrote: >>> On Fri 01-11-24 16:24:55, Stepanov Anatoly wrote: >>>> On 11/1/2024 4:15 PM, Michal Hocko wrote: >>>>> On Fri 01-11-24 14:54:27, Stepanov Anatoly wrote: >>>>>> On 11/1/2024 10:35 AM, Michal Hocko wrote: >>>>>>> On Thu 31-10-24 17:37:12, Stepanov Anatoly wrote: >>>>>>>> If we consider the inheritance approach (prctl + launcher), it's fine until we need to change >>>>>>>> THP mode property for several tasks at once, in this case some batch-change approach needed. >>>>>>> >>>>>>> I do not follow. How is this any different from a single process? Or do >>>>>>> you mean to change the mode for an already running process? >>>>>>> >>>>>> yes, for already running set of processes >>>>> >>>> >>>>> Why is that preferred over setting the policy upfront? >>>> Setting the policy in advance is fine, as the first step to do. >>>> But we might not know in advance >>>> which exact policy is the most beneficial for one set of apps or another. >> >>> >>> How do you plan to find that out when the application is running >>> already? >> For example, if someone willing to compare some DB server performance with THP-off vs THP-on, >> and DB server restart isn't an option. > > So you essentially expect user tell you that they want THP and you want > to make that happen on fly, correct? It is not like there is an actual > monitoring and dynamic policing. For a user/sysadmin this scenario is almost the same as experimenting with global THP settings, but with explicit THP usage, less THP overuse by some random apps, so more predictable. > > If that is the case then I am not really convinced this is a worthwhile > to support TBH. I can see that a workload knows in advance that they > benefit from THP but I am much more dubious about "learning during the > runtime" is a real life thing. I might be wrong of course but if > somebody has performance monitoring that is able to identify performance > bottlenecks based on specific workload then applying THP on the whole > group of proceesses seems like a very crude way to deal with that. I > could see a case for madvice_process(MADV_COLLAPSE) to deal with > specific memory hotspots though. Yes, we have something like this in mind. -- Anatoly Stepanov, Huawei
