Received: by 2002:a05:6902:102b:0:0:0:0 with SMTP id x11csp119087ybt; Thu, 18 Jun 2020 20:13:06 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzHcpcC7ei5RbZ6R0Wthx8doOPHs2pqKy1pPu4sSng1GEvQS3HfhfvzvLn+lP2yNmFHws2B X-Received: by 2002:a50:b0c3:: with SMTP id j61mr1231192edd.349.1592536386680; Thu, 18 Jun 2020 20:13:06 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1592536386; cv=none; d=google.com; s=arc-20160816; b=xF0aUyFi9OGma8sGNhdgmC8mM+6lVVH5GVxOuvBMcobUmBv34NICCAHbtp+FzHmUEU wqYmKua76VI21VvicnjLBrIkYrFl9TSdZBfRrRoKk5sC2TmFIF3tgc16Gbj36cUuobnG vjuZ5Th7TeVMTQUWN4dLq/5JjS/TDGxmplH0EFQfx2Q/gDzAgKGR0xbgOPijws/XOB1L Bsefs9iEyywpKG5duFZSdMqvEB6Yf+ZFo5CI14pm/MQ+dphU+D5raxU8kewqAmnZd1LL PlIxTAKiaxe9g6JBdb71SH3tjQq1ZYd7LZ4s7N+p0GDGimELFVspazcVOhR1pRCS4wuU tEOA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:in-reply-to:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :dkim-signature; bh=GMs1dTUtRlm7p1ATLk5CmBkboJ8dwdec3LertXCUqnc=; b=iocHtL5u4pqMdDXw9m0g4LsWk5L7skybMEfLFdbFTJjqYizTUNFalR65HDTxi7KkWx NTvlnMA5PAdhUnI6RoqjgePWnv6n+IGX7bpM1naOYpQk4O/12Ss9gOqM4CkOIMzetux1 eu0UmUpaFvio/7MoWKCfL6FxUib22A2J/TX3GJLmrzorY4UOQ2oqEYlb/gsB1z6mmHbE i3harQy+ApBRKplu5vomyRS6JQocwGTJXkYHv+MmIZahEww69nof4jN4DAWqtMNY1fhM zJczKiea+iLFvzEiXV0HNAPTZ/XM97efaALsZJIUtSf5qZQQnAxSTeTG7/cWVQ0OD4yW Tk7Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@infradead.org header.s=bombadil.20170209 header.b=JaUPTqF+; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id h2si3254693eji.77.2020.06.18.20.12.44; Thu, 18 Jun 2020 20:13:06 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=fail header.i=@infradead.org header.s=bombadil.20170209 header.b=JaUPTqF+; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729278AbgFSBFQ (ORCPT + 99 others); Thu, 18 Jun 2020 21:05:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40252 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726573AbgFSBFQ (ORCPT ); Thu, 18 Jun 2020 21:05:16 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41E98C06174E; Thu, 18 Jun 2020 18:05:16 -0700 (PDT) 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=GMs1dTUtRlm7p1ATLk5CmBkboJ8dwdec3LertXCUqnc=; b=JaUPTqF+cHwtDddl5QLHYQLOtF NXT5zalnO2mbkuYv8/gsTctH3kewJK8s82hjLGPaIJaMQguP/wtwsc3Pie3YDpZ3tIrs35shKBeAV giB46lFiK7WdaCp57s0Lr8sZmsp5H8wMHpSF9ca56Z07uewn/qUAxKSlcn2oUt4xBhJeXXv/ifCjp EItlcX+ugstMIAN+L+hw6i8jxCbud4Yo7Oj7btNKlbRF44cfI2Y1Lrz3yz+3SyAVkJLr5uQytkabw MCiiKTNeQENQG6EDxRVtntXcxNJ1S65IGvanPzj6om+caGrJYPGvIsQoLo8wSflXgMGA+/YrQ3i9A Q31Bvr2Q==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jm5Sz-0007n5-Sh; Fri, 19 Jun 2020 01:05:13 +0000 Date: Thu, 18 Jun 2020 18:05:13 -0700 From: Matthew Wilcox To: "Derrick, Jonathan" Cc: "dhowells@redhat.com" , "linux-fsdevel@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: Parallel compilation performance regression Message-ID: <20200619010513.GW8681@bombadil.infradead.org> References: 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 Thu, Jun 18, 2020 at 11:52:55PM +0000, Derrick, Jonathan wrote: > Hi David, > > I've been experiencing a performance regression when running a parallel > compilation (eg, make -j72) on recent kernels. I bet you're using a version of make which predates 4.3: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0ddad21d3e99c743a3aa473121dc5561679e26bb