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=-5.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 C851FC433DF for ; Fri, 19 Jun 2020 01:05:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9BCC1207FC for ; Fri, 19 Jun 2020 01:05:21 +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="JaUPTqF+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728868AbgFSBFQ (ORCPT ); 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-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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