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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 3D2ECC43603 for ; Wed, 11 Dec 2019 14:46:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0EF5A2173E for ; Wed, 11 Dec 2019 14:46:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576075579; bh=XUPg0jKEJbOe5bostq1S7exSkK2zO+9rqUlma2uNRcw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Z4PxtD22fTkd8o2fhFFT6mjKjCVxGvxFcG6DZjGvm/BusalmDX/lMadRbHNaMMiwp Hek73Y3KIR1XgtFDvnwdEiMl5kCKDhfBiuKAXTEBLDd/WEBHEP5xvQQ3brfANwijhC vFmlp/JKxyaoaH20TgUNAm+b5xec0jdx46rnLbjY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729894AbfLKOqS (ORCPT ); Wed, 11 Dec 2019 09:46:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:43336 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729689AbfLKOqR (ORCPT ); Wed, 11 Dec 2019 09:46:17 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8A2BD208C3; Wed, 11 Dec 2019 14:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576075577; bh=XUPg0jKEJbOe5bostq1S7exSkK2zO+9rqUlma2uNRcw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2VBTltrES4sUwFNPERJVMiY/DKSZlenMMgpcxjxDdM1Tmbz5J/w4HyvjWPCnpAl3z FiDvTwNQ/UWLO69RVIKyOsbMYNfkgTmnCeYKt2DzN9a/1h+l6TQkjF0k/YiZtDB0gY yFstLUgP12iqfq8U9/xH3i8pNeIycO8ekT3RKpu0= Date: Wed, 11 Dec 2019 15:46:14 +0100 From: Greg KH To: "zhangyi (F)" Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, cl@linux.com, mgalbraith@suse.de, mhocko@suse.com, torvalds@linux-foundation.org, umgwanakikbuti@gmail.com, wagi@monom.org, stable-commits@vger.kernel.org, "Wangkefeng (Maro)" , Xie XiuQi Subject: Re: Patch "mm, vmstat: make quiet_vmstat lighter" has been added to the 4.4-stable tree Message-ID: <20191211144614.GA637714@kroah.com> References: <156442332854185@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 11, 2019 at 10:32:49PM +0800, zhangyi (F) wrote: > Hi, all > > We find a performance degradation under lmbench af_unix[1] test case after > mergeing this patch on my x86 qemu 4.4 machine. The test result is basically > stable for each teses. > > Host machine: CPU: Intel(R) Xeon(R) CPU E5-2690 v3 > CPU(s): 48 > MEM: 193047 MB > > Guest machine: CPU: QEMU Virtual CPU version 2.5+ > CPU(s): 8 > MEM: 26065 MB > > Before this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 133.7073 microseconds > > After this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 156.4722 microseconds > > If we set task to a constant cpu, the degradation does not appear. > > Before this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 17.9296 microseconds > > After this patch: > [root@localhost ~]# lmbench-3.0-a9/bin/x86_64-linux-gnu/lat_unix -P 1 > AF_UNIX sock stream latency: 17.7500 microseconds > > We also test it on the aarch64 hi1215 machine with 8 cpu cores. > > Before this patch: > [root@localhost ~]# ./lat_unix -P 1 > AF_UNIX sock stream latency: 30.7 microseconds > > After this patch: > [root@localhost ~]# ./lat_unix -P 1 > AF_UNIX sock stream latency: 37.5 microseconds > > Accessories included my reproduce config for x86 qemu. Any thoughts? This fixes a bug, as reported by Daniel Wagner. So it's probably better to have a stable system instead of a broken one, right? :) Daniel can provide more information if needed. What about when you run your tests on a 4.9 or newer kernel that already has this integrated? thanks, greg k-h