* KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> [2011-04-01 22:21:26]: > > * KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> [2011-04-01 16:56:57]: > > > > > Hi > > > > > > > > 1) zone reclaim doesn't work if the system has multiple node and the > > > > > workload is file cache oriented (eg file server, web server, mail server, et al). > > > > > because zone recliam make some much free pages than zone->pages_min and > > > > > then new page cache request consume nearest node memory and then it > > > > > bring next zone reclaim. Then, memory utilization is reduced and > > > > > unnecessary LRU discard is increased dramatically. > > > > > > > > > > SGI folks added CPUSET specific solution in past. (cpuset.memory_spread_page) > > > > > But global recliam still have its issue. zone recliam is HPC workload specific > > > > > feature and HPC folks has no motivation to don't use CPUSET. > > > > > > > > I am afraid you misread the patches and the intent. The intent to > > > > explictly enable control of unmapped pages and has nothing > > > > specifically to do with multiple nodes at this point. The control is > > > > system wide and carefully enabled by the administrator. > > > > > > Hm. OK, I may misread. > > > Can you please explain the reason why de-duplication feature need to selectable and > > > disabled by defaut. "explicity enable" mean this feature want to spot corner case issue?? > > > > Yes, because given a selection of choices (including what you > > mentioned in the review), it would be nice to have > > this selectable. > > It's no good answer. :-/ I am afraid I cannot please you with my answers > Who need the feature and who shouldn't use it? It this enough valuable for enough large > people? That's my question point. > You can see the use cases documented, including when running Linux as a guest under other hypervisors, today we have a choice of not using host page cache with cache=none, but nothing the other way round. There are other use cases for embedded folks (in terms of controlling unmapped page cache), please see previous discussions. -- Three Cheers, Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>