On Thu, Jun 12, 2014 at 01:24:34AM +0400, Vladimir Davydov wrote: > On Tue, Jun 10, 2014 at 07:18:34PM +0400, Vladimir Davydov wrote: > > On Tue, Jun 10, 2014 at 09:26:19AM -0500, Christoph Lameter wrote: > > > On Tue, 10 Jun 2014, Vladimir Davydov wrote: > > > > > > > Frankly, I incline to shrinking dead SLAB caches periodically from > > > > cache_reap too, because it looks neater and less intrusive to me. Also > > > > it has zero performance impact, which is nice. > > > > > > > > However, Christoph proposed to disable per cpu arrays for dead caches, > > > > similarly to SLUB, and I decided to give it a try, just to see the end > > > > code we'd have with it. > > > > > > > > I'm still not quite sure which way we should choose though... > > > > > > Which one is cleaner? > > > > To shrink dead caches aggressively, we only need to modify cache_reap > > (see https://lkml.org/lkml/2014/5/30/271). > > Hmm, reap_alien, which is called from cache_reap to shrink per node > alien object arrays, only processes one node at a time. That means with > the patch I gave a link to above it will take up to > (REAPTIMEOUT_AC*nr_online_nodes) seconds to destroy a virtually empty > dead cache, which may be quite long on large machines. Of course, we can > make reap_alien walk over all alien caches of the current node, but that > will probably hurt performance... Hmm, maybe we have a few of objects on other node, doesn't it? BTW, I have a question about cache_reap(). If there are many kmemcg users, we would have a lot of slab caches and just to traverse slab cache list could take some times. Is it no problem? Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>