On Tue, Jul 3, 2018 at 12:13 PM Kirill Tkhai <ktkhai@xxxxxxxxxxxxx> wrote: > > On 03.07.2018 20:58, Matthew Wilcox wrote: > > On Tue, Jul 03, 2018 at 06:46:57PM +0300, Kirill Tkhai wrote: > >> shrinker_idr now contains only memcg-aware shrinkers, so all bits from memcg map > >> may be potentially populated. In case of memcg-aware shrinkers and !memcg-aware > >> shrinkers share the same numbers like you suggest, this will lead to increasing > >> size of memcg maps, which is bad for memory consumption. So, memcg-aware shrinkers > >> should to have its own IDR and its own numbers. The tricks like allocation big > >> IDs for !memcg-aware shrinkers seem bad for me, since they make the code more > >> complicated. > > > > Do we really have so very many !memcg-aware shrinkers? > > > > $ git grep -w register_shrinker |wc > > 32 119 2221 > > $ git grep -w register_shrinker_prepared |wc > > 4 13 268 > > (that's an overstatement; one of those is the declaration, one the definition, > > and one an internal call, so we actually only have one caller of _prepared). > > > > So it looks to me like your average system has one shrinker per > > filesystem, one per graphics card, one per raid5 device, and a few > > miscellaneous. I'd be shocked if anybody had more than 100 shrinkers > > registered on their laptop. > > > > I think we should err on the side of simiplicity and just have one IDR for > > every shrinker instead of playing games to solve a theoretical problem. > > It just a standard situation for the systems with many containers. Every mount > introduce a new shrinker to the system, so it's easy to see a system with > 100 or ever 1000 shrinkers. AFAIR, Shakeel said he also has the similar > configurations. > I can say on our production systems, a couple thousand shrinkers is normal. Shakeel
