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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 BE28EC433ED for ; Thu, 29 Apr 2021 21:32:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8F38261445 for ; Thu, 29 Apr 2021 21:32:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235775AbhD2Vc4 (ORCPT ); Thu, 29 Apr 2021 17:32:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:34686 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237184AbhD2Vc4 (ORCPT ); Thu, 29 Apr 2021 17:32:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1799D613AD; Thu, 29 Apr 2021 21:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619731929; bh=k33BblzLXcEhwHXhnkR3kTkgLIccxbjvGRLQ0ZE5B5A=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MSvkhUVj/2YSAEDJhrz4em3iJ8ZGgdhGZzZcS/13pBc45UMH7zzi3l6QJvlj5ssZ7 v41G6AdmkQrbQgf34nQJFpll2u1iK3MZLQJysXzpG8YCA1Je2gfXT4rZML0f8b4BwF ZHqa9gMSGZxeix8zpO7Bf0mt6hzu0bLKdz8Ig6VnCxBeHK9QgHl3Gd9y2RsbXXmslS 8VLBktF1mxpu0OF686yTaBEwPxRB1kGKbQ5yY9oJ7XMYfDtWEnLSnjF1fulNdw3KEq 5icvRNr3/lzXrB32NU7NEGc+btMOwPKusonrOV/GSgGgVpUGUKNPchb34+onjYHF/J irnV636ZmBhbA== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 6977B4034C; Thu, 29 Apr 2021 18:32:06 -0300 (-03) Date: Thu, 29 Apr 2021 18:32:06 -0300 From: Arnaldo Carvalho de Melo To: Muni Sekhar Cc: peter enderborg , Greg KH , kernelnewbies , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: Scheduler benchmarks Message-ID: References: <20200818143633.GA628293@kroah.com> <20200818171457.GA736234@kroah.com> <20200818173656.GA748290@kroah.com> <84362b8b-971f-fb89-115d-41d2457c24fd@sony.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org Em Wed, Aug 19, 2020 at 03:46:06PM +0530, Muni Sekhar escreveu: > On Tue, Aug 18, 2020 at 11:45 PM peter enderborg wrote: > > On 8/18/20 7:53 PM, Muni Sekhar wrote: > > > On Tue, Aug 18, 2020 at 11:06 PM Greg KH wrote: > > >> On Tue, Aug 18, 2020 at 11:01:35PM +0530, Muni Sekhar wrote: > > >>> On Tue, Aug 18, 2020 at 10:44 PM Greg KH wrote: > > >> Those are _very_ different kernel versions, with many years and tens of > > >> thousands of different changes between them. > > >> > > >> Hopefully the newer kernel is faster, so just stick with that :) > > > But unfortunately the newer kernel is very slow, that is the reason > > > for starting this investigation :) > > > Any type of help, and guidelines to dive deeper will be highly appreciated. > > > > On the 4.4 kernel you dont have > > > > +CONFIG_RETPOLINE=y > > +CONFIG_INTEL_RDT=y > Thanks! That is helpful. Yes, I see 4.4 kernel don't have the above > two config options. > What analysis can be done to narrow down the root cause? > Any example of reference could be helpful to understand. This made me remember Lisbon: http://vger.kernel.org/~acme/perf/bpf-is-eating-the-world-dont-you-see-lpc-lisbon-2019/#/8/2 Greg was there when this slide was first shown... ;-) Look at the icache misses when the kernel is entered (syscall entry). Then add this to the kernel command line: "nospectre_v1 nospectre_v2" And see what happens: http://vger.kernel.org/~acme/perf/bpf-is-eating-the-world-dont-you-see-lpc-lisbon-2019/#/8/3 So using these (and any new ones related to disabling hardware flaw mitigation) maybe a way to analyse this, if you haven't figured this out yet, sorry for the huge delay in replying 8-) - Arnaldo > > > > And your base is very different two. > > > > Try to use mainline on both system and see. > > > > You can also use the same base kernel version from ubuntu and > > > > run your test. > > > > > > >> greg k-h > > > > > > > > > > > -- > Thanks, > Sekhar -- - Arnaldo