Hello KOSAKI, On Tue, May 01, 2012 at 09:20:27PM -0400, KOSAKI Motohiro wrote: [...] > >It would be great indeed, but so far I don't see much that > >vmevent could share. Plus, sharing the code at this point is not > >that interesting; it's mere 500 lines of code (comparing to > >more than 10K lines for cgroups, and it's not including memcg_ > >hooks and logic that is spread all over mm/). > > > >Today vmevent code is mostly an ABI implementation, there is > >very little memory management logic (in contrast to the memcg). > > But, if it doesn't work desktop/server area, it shouldn't be merged. What makes you think that vmevent won't work for desktop or servers? :-) E.g. for some servers you don't always want memcg, really. Suppose, a kvm farm or a database server. Sometimes there's really no need for the memcg, but there's still a demand for low memory notifications. Current Linux desktops don't use any notifications at all, I think. So nothing to say about, neither on cgroup's nor on vmevent's behalf. I hardly imagine why desktop would use the whole memcg thing, but still have a use case for memory notifications. > We have to consider the best design before kernel inclusion. They cann't > be separeted to discuss. Of course, no objections here. But I somewhat disagree with the "best design" term. Which design is better, reading a file via read() or mmap()? It depends. Same here. So far, I see that memcg has its own cons, some are "by design" and some because of incomplete features (e.g. slab accounting, which, if accepted as is, seem to have its own design flaws). memcg has many pros as well, the main goodness of memcg (for memory notifications case) is rate limited events, which is a very cool feature, and memcg has the feature because it's so much tied with the mm subsystem. But, as I said in my previus email, making memcg backend for vmevents seems doable. We'd only need to place a vmevents hook into mm/memcontrol.c:memcg_check_events() and export mem_cgroup_usage() call. So vmevent makes it possible for things to work with cgroups and without cgroups, everybody's happy. Thanks, p.s. I'm not the vmevents author, plus I use both memcg and vmevents. That makes me think that I'm pretty unbiased here. ;-) -- Anton Vorontsov Email: cbouatmailru@xxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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>