From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f182.google.com (mail-pd0-f182.google.com [209.85.192.182]) by kanga.kvack.org (Postfix) with ESMTP id DF5606B013F for ; Wed, 11 Jun 2014 04:07:46 -0400 (EDT) Received: by mail-pd0-f182.google.com with SMTP id y13so1121178pdi.13 for ; Wed, 11 Jun 2014 01:07:46 -0700 (PDT) Received: from lgemrelse7q.lge.com (LGEMRELSE7Q.lge.com. [156.147.1.151]) by mx.google.com with ESMTP id qs8si37103202pbb.206.2014.06.11.01.07.44 for ; Wed, 11 Jun 2014 01:07:45 -0700 (PDT) Date: Wed, 11 Jun 2014 17:11:39 +0900 From: Joonsoo Kim Subject: Re: [PATCH -mm v2 8/8] slab: make dead memcg caches discard free slabs immediately Message-ID: <20140611081139.GA28258@js1304-P5Q-DELUXE> References: <27a202c6084d6bb19cc3e417793f05104b908ded.1402060096.git.vdavydov@parallels.com> <20140610074317.GE19036@js1304-P5Q-DELUXE> <20140610100313.GA6293@esperanza> <20140610151830.GA8692@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140610151830.GA8692@esperanza> Sender: owner-linux-mm@kvack.org List-ID: To: Vladimir Davydov Cc: Christoph Lameter , akpm@linux-foundation.org, rientjes@google.com, penberg@kernel.org, hannes@cmpxchg.org, mhocko@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org 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). > > To zap object arrays for dead caches (this is what this patch does), we > have to: > - set array_cache->limit to 0 for each per cpu, shared, and alien array > caches on kmem_cache_shrink; > - make cpu/node hotplug paths init new array cache sizes to 0; > - make free paths (__cache_free, cache_free_alien) handle zero array > cache size properly, because currently they doesn't. > > So IMO the first one (reaping dead caches periodically) requires less > modifications and therefore is cleaner. Yeah, I also like the first one. Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org