fs: per-zone dentry and inode LRU
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From: Dave Chinner on 30 Jun 2010 06:20 On Thu, Jun 24, 2010 at 01:03:03PM +1000, npiggin(a)suse.de wrote: > Per-zone LRUs and shrinkers for dentry and inode caches. > > Signed-off-by: Nick Piggin <npiggin(a)suse.de> This destroys any notion we have of global LRU-ness of inode and dentry caches, doesn't it? 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? Cheers, Dave. -- Dave Chinner david(a)fromorbit.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Nick Piggin on 30 Jun 2010 10:40
On Wed, Jun 30, 2010 at 08:09:37PM +1000, Dave Chinner wrote: > On Thu, Jun 24, 2010 at 01:03:03PM +1000, npiggin(a)suse.de wrote: > > Per-zone LRUs and shrinkers for dentry and inode caches. > > > > Signed-off-by: Nick Piggin <npiggin(a)suse.de> > > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |