Hi Andrew, On Tue, Mar 07, 2017 at 02:43:38PM -0800, Andrew Morton wrote: > On Tue, 7 Mar 2017 11:05:45 +0100 Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > On Fri 03-03-17 16:10:27, Andrew Morton wrote: > > > On Thu, 2 Mar 2017 17:30:54 +0100 Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > > > > > It's not that I think you're wrong: it *is* an implementation detail. > > > > > But we take a bit of incoherency from batching all over the place, so > > > > > it's a little odd to take a stand over this particular instance of it > > > > > - whether demanding that it'd be fixed, or be documented, which would > > > > > only suggest to users that this is special when it really isn't etc. > > > > > > > > I am not aware of other counter printed in smaps that would suffer from > > > > the same problem, but I haven't checked too deeply so I might be wrong. > > > > > > > > Anyway it seems that I am alone in my position so I will not insist. > > > > If we have any bug report then we can still fix it. > > > > > > A single lru_add_drain_all() right at the top level (in smaps_show()?) > > > won't kill us > > > > I do not think we want to put lru_add_drain_all cost to a random > > process reading /proc/<pid>/smaps. > > Why not? It's that process which is calling for the work to be done. > > > If anything the one which does the > > madvise should be doing this. > > But it would be silly to do extra work in madvise() if nobody will be > reading smaps for the next two months. > > How much work is it anyway? What would be the relative impact upon a > smaps read? I agree only if the draining guarantees all of mapped pages in the range could be marked to lazyfree. However, it's not true because there are a few of logics to skip the page marking in madvise_free_pte_range. So, my conclusion is drainning helps a bit but not gaurantees. In such case, IMHO, let's not do the effort to make better. Thanks. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
