On Mon, 18 Jan 2021, Michal Hocko wrote: > > Hm this would be similar to recommending a periodical echo > drop_caches > > operation. We actually discourage from that (and yeah, some tools do that, and > > we now report those in dmesg). I believe the kernel should respond to memory > > pressure and not OOM prematurely by itself, including SLUB. > > Absolutely agreed! Partial caches are a very deep internal > implementation detail of the allocator and admin has no bussiness into > fiddling with that. This would only lead to more harm than good. > Comparision to drop_caches is really exact! Really? The maximum allocation here has a upper boundary that depends on the number of possible partial per cpu slabs. There is a worst case scenario that is not nice and wastes some memory but it is not an OOM situation and the system easily recovers from it. The slab shrinking is not needed but if you are concerned about reclaiming more memory right now then I guess you may want to run the slab shrink operation. Dropping the page cache is bad? Well sometimes you want more free memory due to a certain operation that needs to be started and where you do not want the overhead of page cache processing. You can go crazy and expect magical things from either operation. True.
