On Mon, Jul 16, 2018 at 11:09:01AM +0200, Michal Hocko wrote: > On Fri 13-07-18 10:36:14, Dave Chinner wrote: > [...] > > By limiting the number of negative dentries in this case, internal > > slab fragmentation is reduced such that reclaim cost never gets out > > of control. While it appears to "fix" the symptoms, it doesn't > > address the underlying problem. It is a partial solution at best but > > at worst it's another opaque knob that nobody knows how or when to > > tune. > > Would it help to put all the negative dentries into its own slab cache? Maybe the dcache should be more sensitive to its own needs. In __d_alloc, it could check whether there are a high proportion of negative dentries and start recycling some existing negative dentries.
