From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4248BC35647 for ; Fri, 21 Feb 2020 10:58:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 16B462073A for ; Fri, 21 Feb 2020 10:58:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="H1wPemHm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727352AbgBUK6M (ORCPT ); Fri, 21 Feb 2020 05:58:12 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:42590 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727034AbgBUK6M (ORCPT ); Fri, 21 Feb 2020 05:58:12 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=mN2ry1gqY7iOMcWFX6PDe/yjH041nighn7Vq+N4RRho=; b=H1wPemHmzR69jODR1q5tMyaExP csN9+Fz/Qp/t7ylh5ctVYkQQxo6+Tnrlz0YcL3S2+RiwHRJXxqm6ONIVZrVtVSI5WXolNN8MJFXcZ TeiZne17kmeufh8+/NxgaiJKvUdnrWvZq6VvtmMg1SgCitrRYHo6gaSj3FWXv5oittIu39WYS43/x iWONuayzK5JCgiD640AFTogd6fW1rbCh1CK9JmHJtBx379EDQPvKP7BgfI0qV0+Hg48cUtKxG9otZ 8V4I651dB49/+Hwls+Vi12u4lH4ZTsgJ+o5VIIG556die7xcP5ycgaXQs9coEL2SjoJLvPOj9PWaP A+mc8xCQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j560R-0006OA-9n; Fri, 21 Feb 2020 10:58:03 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id D3B1930008D; Fri, 21 Feb 2020 11:56:07 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 025BC2014E22A; Fri, 21 Feb 2020 11:58:00 +0100 (CET) Date: Fri, 21 Feb 2020 11:58:00 +0100 From: Peter Zijlstra To: Feng Tang Cc: kernel test robot , Jiri Olsa , Ingo Molnar , Vince Weaver , Jiri Olsa , Alexander Shishkin , Arnaldo Carvalho de Melo , Arnaldo Carvalho de Melo , Linus Torvalds , "Naveen N. Rao" , Ravi Bangoria , Stephane Eranian , Thomas Gleixner , LKML , lkp@lists.01.org, andi.kleen@intel.com, ying.huang@intel.com Subject: Re: [LKP] Re: [perf/x86] 81ec3f3c4c: will-it-scale.per_process_ops -5.5% regression Message-ID: <20200221105800.GF18400@hirez.programming.kicks-ass.net> References: <20200205123216.GO12867@shao2-debian> <20200205125804.GM14879@hirez.programming.kicks-ass.net> <20200221080325.GA67807@shbuild999.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200221080325.GA67807@shbuild999.sh.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 21, 2020 at 04:03:25PM +0800, Feng Tang wrote: > We checked more on this. We run 14 times test for it, and the > results are consistent about the 5.5% degradation, and we > run the same test on several other platforms, whose test results > are also consistent, though there are no such -5.5% seen. > So likely, this commit changes the layout of the kernel text > and data, which may trigger some cacheline level change. From > the system map of the 2 kernels, a big trunk of symbol's address > changes which follow the global "pmu", > > 5.0-rc6-systemap: > > ffffffff8221d000 d pmu > ffffffff8221d100 d pmc_reserve_mutex > ffffffff8221d120 d amd_f15_PMC53 > ffffffff8221d160 d amd_f15_PMC50 > > 5.0-rc6+pmu-change-systemap: > > ffffffff8221d000 d pmu > ffffffff8221d120 d pmc_reserve_mutex > ffffffff8221d140 d amd_f15_PMC53 > ffffffff8221d180 d amd_f15_PMC50 > > But we can hardly identify which exact symbol is responsible > for the change, as too many symbols are offseted. *groan*, that's horrible. Thanks for digging into this.