On Mon, Jun 04, 2012 at 09:17:22PM +0900, Minchan Kim wrote: [...] > But keep in mind about killing. killer should be a kernel, not user. > https://lkml.org/lkml/2011/12/19/330 There you're discussing out-of-memory condition vs. low memory situation, and I don't see LMK as a substitution for the OOMK, or vice versa. LMK triggers when we have plenty of free memory (and thus time); and OOMK is a last resort thing: it is super-fast, as the kernel may have literally nothing to do but start killing tasks. Sure, if LMK won't react fast and low-memory turns into "out of memory", then OOMK will "help", which is totally fine. And it is no different from current in-kernel Android low memory killer (which gives no guarantees that OOMK will not trigger, it is still possible to make OOM condition, even with LMK enabled). Anyway, personally I don't mind if LMK would live in the kernel, but I don't see it as a mandatory thing (unlike OOMK, which is kernel-only thing, of course). > > > Frankly speaking, I don't know vmevent's other use cases except low memory notification > > > > I won't speak for realistic use-cases, but that is what comes to > > mind: > > > > - DB can grow its caches/in-memory indexes infinitely, and start dropping > > them on demand (based on internal LRU list, for example). No more > > guessed/static configuration for DB daemons? > > - Assuming VPS hosting w/ dynamic resources management, notifications > > would be useful to readjust resources? > > - On desktops, apps can drop their caches on demand if they want to > > and can avoid swap activity? > > I don't mean VMEVENT_ATTR_LOWMEM_PAGES but following as, > > VMEVENT_ATTR_NR_FREE_PAGES > VMEVENT_ATTR_NR_SWAP_PAGES > VMEVENT_ATTR_NR_AVAIL_PAGES > > I'm not sure how it is useful. Yep, these raw values are mostly useless, and personally I don't use these plain attributes. I use heuristics, i.e. "blended" attributes. If we can come up with levels-based approach w/o using vmstat, well.. OK then. But note that we actually want to know how much "free", "cheap to reclaim" and "can reclaim, but at cost" pages there are. It should not be just "ouch, we're out of cheap pages" signal, since the whole point of Android low memory killer is to act in advance, its idea is to try to free memory before the condition happens, and thus make the phone UI more smooth. And the threshold is actually load/HW specific, so I guess folks want to tune it (e.g. "trigger when there are XX MB of 'cheap to reclaim' pages left"). Thanks, -- 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>