From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751664AbdI2IPO (ORCPT ); Fri, 29 Sep 2017 04:15:14 -0400 Received: from mail-ve1eur01on0095.outbound.protection.outlook.com ([104.47.1.95]:35520 "EHLO EUR01-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750847AbdI2IPK (ORCPT ); Fri, 29 Sep 2017 04:15:10 -0400 Subject: Re: [PATCH] mm: Make count list_lru_one::nr_items lockless To: Andrew Morton Cc: vdavydov.dev@gmail.com, apolyakov@beget.ru, linux-kernel@vger.kernel.org, linux-mm@kvack.org, aryabinin@virtuozzo.com References: <150583358557.26700.8490036563698102569.stgit@localhost.localdomain> <20170927141530.25286286fb92a2573c4b548f@linux-foundation.org> <20170928140230.a9a0cd44a09eae9441a83bdc@linux-foundation.org> From: Kirill Tkhai Message-ID: <137a49f9-8286-8bf4-91c5-37b5f6b5a842@virtuozzo.com> Date: Fri, 29 Sep 2017 11:15:04 +0300 User-Agent: Mozilla/5.0 (X11; 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Did you not run the same >>> performance tests after applying it? >> >> I've just detected the such high usage of shrink slab on production node. It's rather >> difficult to make it use another kernel, than it uses, only kpatches are possible. >> So, I haven't estimated how it acts on node's performance. >> On test node I see, that the patch obviously removes raw_spin_lock from perf profile. >> So, it's a little bit untested in this way. > > Well that's a problem. The patch increases list_lru.o text size by a > lot (4800->5696) which will have a cost. And we don't have proof that > any benefit is worth that cost. It shouldn't be too hard to cook up a > synthetic test to trigger memcg slab reclaim and then run a > before-n-after benchmark? Ok, then, please, ignore this for a while, I'll try to do it a little bit later. Kirill