From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756988AbcH3BHC (ORCPT ); Mon, 29 Aug 2016 21:07:02 -0400 Received: from smtprelay0118.hostedemail.com ([216.40.44.118]:59777 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754321AbcH3BHA (ORCPT ); Mon, 29 Aug 2016 21:07:00 -0400 X-Session-Marker: 6A6F6540706572636865732E636F6D X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,joe@perches.com,:::::::::::::::::,RULES_HIT:41:355:379:541:599:966:973:988:989:1260:1277:1311:1313:1314:1345:1359:1373:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2196:2199:2393:2559:2562:2828:3138:3139:3140:3141:3142:3353:3622:3865:3866:3867:3868:3870:3872:4321:4385:5007:6630:7903:10004:10400:10848:11026:11232:11658:11914:12043:12296:12438:12740:13069:13311:13357:13439:13894:14659:14721:21080:30034:30054:30064:30091,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:1,LUA_SUMMARY:none X-HE-Tag: bike89_1f91261e18729 X-Filterd-Recvd-Size: 2603 Message-ID: <1472519215.5512.30.camel@perches.com> Subject: Re: [PATCH v4 resend] mm/slab: Improve performance of gathering slabinfo stats From: Joe Perches To: Aruna Ramakrishna , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Mike Kravetz , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton Date: Mon, 29 Aug 2016 18:06:55 -0700 In-Reply-To: <1472517876-26814-1-git-send-email-aruna.ramakrishna@oracle.com> References: <1472517876-26814-1-git-send-email-aruna.ramakrishna@oracle.com> Content-Type: text/plain; charset="ISO-8859-1" X-Mailer: Evolution 3.18.5.2-0ubuntu3 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2016-08-29 at 17:44 -0700, Aruna Ramakrishna wrote: > This patch optimizes 'cat /proc/slabinfo' by maintaining a counter for > total number of allocated slabs per node, per cache. [] > We tested this after > growing the dentry cache to 70GB, and the performance improved from 2s to > 5ms. Seems sensible, thanks. One completely trivial note: > diff --git a/mm/slab.c b/mm/slab.c [] > @@ -1394,24 +1395,27 @@ slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid) >   for_each_kmem_cache_node(cachep, node, n) { >   unsigned long active_objs = 0, num_objs = 0, free_objects = 0; >   unsigned long active_slabs = 0, num_slabs = 0; > + unsigned long num_slabs_partial = 0, num_slabs_free = 0; > + unsigned long num_slabs_full; [] > + num_slabs_full = num_slabs - > + (num_slabs_partial + num_slabs_free); vs > @@ -4111,6 +4119,8 @@ void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo) >   unsigned long num_objs; >   unsigned long active_slabs = 0; >   unsigned long num_slabs, free_objects = 0, shared_avail = 0; > + unsigned long num_slabs_partial = 0, num_slabs_free = 0; > + unsigned long num_slabs_full = 0; [] > + num_slabs_full = num_slabs - (num_slabs_partial + num_slabs_free); It seems odd to have different initialization styles for num_slabs_full.  It seems the second one doesn't need to be initialized. It'd also be nicer I think if the two declarations blocks had more similar layouts. Maybe in a follow-on patch.  Or not.  Your choice.