On Tue, 2 Jul 2019 14:37:30 -0400 Waiman Long <long...@redhat.com> wrote:
> Currently, a value of '1" is written to /sys/kernel/slab/<slab>/shrink > file to shrink the slab by flushing all the per-cpu slabs and free > slabs in partial lists. This applies only to the root caches, though. > > Extends this capability by shrinking all the child memcg caches and > the root cache when a value of '2' is written to the shrink sysfs file. Why? Please fully describe the value of the proposed feature to or users. Always. > > ... > > --- a/Documentation/ABI/testing/sysfs-kernel-slab > +++ b/Documentation/ABI/testing/sysfs-kernel-slab > @@ -429,10 +429,12 @@ KernelVersion: 2.6.22 > Contact: Pekka Enberg <penb...@cs.helsinki.fi>, > Christoph Lameter <c...@linux-foundation.org> > Description: > - The shrink file is written when memory should be reclaimed from > - a cache. Empty partial slabs are freed and the partial list is > - sorted so the slabs with the fewest available objects are used > - first. > + A value of '1' is written to the shrink file when memory should > + be reclaimed from a cache. Empty partial slabs are freed and > + the partial list is sorted so the slabs with the fewest > + available objects are used first. When a value of '2' is > + written, all the corresponding child memory cgroup caches > + should be shrunk as well. All other values are invalid. One would expect this to be a bitfield, like /proc/sys/vm/drop_caches. So writing 3 does both forms of shrinking. Yes, it happens to be the case that 2 is a superset of 1, but what about if we add "4"?
