From: Christopher Lameter <c...@linux.com> Date: Wed, May 15, 2019 at 7:00 AM To: Roman Gushchin Cc: Andrew Morton, Shakeel Butt, <linux...@kvack.org>, <linux-kernel@vger.kernel.org>, <kernel-t...@fb.com>, Johannes Weiner, Michal Hocko, Rik van Riel, Vladimir Davydov, <cgro...@vger.kernel.org>
> On Tue, 14 May 2019, Roman Gushchin wrote: > > > To make this possible we need to introduce a new percpu refcounter > > for non-root kmem_caches. The counter is initialized to the percpu > > mode, and is switched to atomic mode after deactivation, so we never > > shutdown an active cache. The counter is bumped for every charged page > > and also for every running allocation. So the kmem_cache can't > > be released unless all allocations complete. > > Increase refcounts during each allocation? Looks to be quite heavy > processing. Not really, it's a percpu refcnt. Basically the memcg's percpu_ref_tryget* is replaced with kmem_cache's percpu_ref_tryget, so, no additional processing.
