From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [patch 51/52] fs: per-zone dentry and inode LRU Date: Wed, 30 Jun 2010 22:13:18 +1000 Message-ID: <20100630121318.GF21358@laptop> References: <20100624030212.676457061@suse.de> <20100624030733.869946613@suse.de> <20100630100937.GJ24712@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, John Stultz , Frank Mayhar To: Dave Chinner Return-path: Content-Disposition: inline In-Reply-To: <20100630100937.GJ24712@dastard> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Jun 30, 2010 at 08:09:37PM +1000, Dave Chinner wrote: > On Thu, Jun 24, 2010 at 01:03:03PM +1000, npiggin@suse.de wrote: > > Per-zone LRUs and shrinkers for dentry and inode caches. > > > > Signed-off-by: Nick Piggin > > This destroys any notion we have of global LRU-ness of inode and > dentry caches, doesn't it? Yes. > Can you outline in more detail what sort > of reclaim pattern this results in. e.g. is a workload running on > a single node now effectively limited to a dentry/icache size within > the local node because of local node slab allocation and per-zone > reclaim? No, it will just make the vfs cache reclaim work similarly to pagecache reclaim. Reclaimers (kswapd) can work on node local memory; memory pressure in a particular zone can be targetted specifically instead of shrinking all zones until it is OK; zone reclaim will work properly for vfs caches; partitioning of workloads can be better. Workload on a single node can certainly still use up all global memory if that is how the policy is configured. Global LRU ordering is lost, but it is approximated when there is a global memory shortage by scanning a little from each zone head. When there is a local memory shortage it should be superior because that can be resolved without reclaiming so much memory. Thanks, Nick