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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 8587AC10F13 for ; Tue, 16 Apr 2019 17:37:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4FBAE2073F for ; Tue, 16 Apr 2019 17:37:18 +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="x4x2vc6T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730138AbfDPRhQ (ORCPT ); Tue, 16 Apr 2019 13:37:16 -0400 Received: from merlin.infradead.org ([205.233.59.134]:48482 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727180AbfDPRhQ (ORCPT ); Tue, 16 Apr 2019 13:37:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=rY30XL8+ypP0Pufcsv2Q3EE2EU/yIGQk8HBVJ0EQZHA=; b=x4x2vc6TlE98U3X5q8/uGI7/ZJ HBaixrIn0oxfvX/ejs9xd7blZwGdCu3Mwt9oBuXo02PUHvgMtKimBIGbEyhj32A/3WpUxpZQmPBM4 UVznDYrfjRB6Veski24sMu5Q2qmRsCmnrUttrS/7l+aUh6JX2WtXiUCdSTlsMTUtiaaQkkgKUf4Sg TOxBBbS10v2be5FsYXDD9jj9V9kqaVLlDLIiegxymdG5iro27P8LBXNywhIz1qaeQUFelMJ1F9PS7 W+LelW0Qdr6Ao67WyM0AXZQ2a2V8e9YjGK7i2kBD6opN9VebZ1EPE2hZIVkE1+QjVGZl+sXePPw/s muXAm8Pg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hGS11-0004h4-9K; Tue, 16 Apr 2019 17:37:03 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9E3DA29B27D87; Tue, 16 Apr 2019 19:37:00 +0200 (CEST) Date: Tue, 16 Apr 2019 19:37:00 +0200 From: Peter Zijlstra To: Waiman Long Cc: Ingo Molnar , Will Deacon , Thomas Gleixner , linux-kernel@vger.kernel.org, x86@kernel.org, Davidlohr Bueso , Linus Torvalds , Tim Chen , huang ying Subject: Re: [PATCH-tip 0/2] locking/rwsem: Rwsem rearchitecture part 2 follow-up patches Message-ID: <20190416173700.GQ4038@hirez.programming.kicks-ass.net> References: <20190415205829.32707-1-longman@redhat.com> <20190416131047.GW11158@hirez.programming.kicks-ass.net> <4747d10b-e9a4-f453-ab4e-13fc984a4067@redhat.com> <20190416141747.GN4038@hirez.programming.kicks-ass.net> <18af71ce-1ef3-c6cd-4088-3b2a9bf0016e@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <18af71ce-1ef3-c6cd-4088-3b2a9bf0016e@redhat.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 Tue, Apr 16, 2019 at 01:03:10PM -0400, Waiman Long wrote: > On 04/16/2019 10:17 AM, Peter Zijlstra wrote: > > On Tue, Apr 16, 2019 at 09:18:50AM -0400, Waiman Long wrote: > >> On 04/16/2019 09:10 AM, Peter Zijlstra wrote: > >>> On Mon, Apr 15, 2019 at 04:58:27PM -0400, Waiman Long wrote: > >>>> This series contain 2 follow-up patches to alleviate the performance > >>>> regression found in the page_fault1 test of the will-it-scale benchmark. > >>>> This does not recover all the lost performance, but reclaim a sizeable > >>>> portion of it. > >>>> > >>>> The regression was found on an Intel system. I have run the test on > >>>> an AMD system. The regression wasn't seen there. There are only minor > >>>> variations in performance. Perhaps the page fault path is quite different > >>>> between Intel and AMD systems. > >>> Can you please just fold this back into the appropriate patches? Trying > >>> to review all the back and forth is painful. > >> I will send out an update part 2 patch with patch 1 of this series > >> merged into the writer spinning on reader patch. Patch 2 of this series > >> will be a standalone one. > > Hmm, in that case I can fold it back too. So hold off on sending it. > > > > I thought #2 was a fixup for an earlier patch as well. > > #2 is a performance fix. Of this patch? 206038 N T Apr 13 Waiman Long (7.5K) ├─>[PATCH v4 11/16] locking/rwsem: Enable readers spinning on writer Fixes should have a Fixes: tag. And if the patch it fixes isn't a commit yet, the patch should be refreshed to not need a fix.