On Tue 10-10-17 15:21:53, Shakeel Butt wrote: [...] > On Tue, Oct 10, 2017 at 2:10 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > On Mon 09-10-17 20:17:54, Michal Hocko wrote: > >> the primary concern for this patch was whether we really need/want to > >> charge short therm objects which do not outlive a single syscall. > > > > Let me expand on this some more. What is the benefit of kmem accounting > > of such an object? It cannot stop any runaway as a syscall lifetime > > allocations are bound to number of processes which we kind of contain by > > other means. > > We can contain by limited the number of processes or thread but for us > applications having thousands of threads is very common. So, limiting > the number of threads/processes will not work. Well, the number of tasks is already contained in a way because we do account each task (kernel) stack AFAIR. > > If we do account then we put a memory pressure due to > > something that cannot be reclaimed by no means. Even the memcg OOM > > killer would simply kick a single path while there might be others > > to consume the same type of memory. > > > > So what is the actual point in accounting these? Does it help to contain > > any workload better? What kind of workload? > > > > I think the benefits will be isolation and more accurate billing. As I > have said before we have observed 100s of MiBs in names_cache on many > machines and cumulative amount is not something we can ignore as just > memory overhead. I do agree with Al arguing this is rather dubious and it can add an overhead without a good reason. > > Or am I completely wrong and name objects can outlive a syscall > > considerably? > > > > No, I didn't find any instance of the name objects outliving the syscall. > > Anyways, we can discuss more on names_cache, do you have any objection > regarding charging filp? I think filep makes more sense. But let's drop the names for now. I am not really convinced this is a good idea. -- Michal Hocko SUSE Labs -- 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>
