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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 07F5AECDFD0 for ; Fri, 14 Sep 2018 14:07:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B662A20671 for ; Fri, 14 Sep 2018 14:07:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B662A20671 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=de.ibm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728076AbeINTWC (ORCPT ); Fri, 14 Sep 2018 15:22:02 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:52064 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726845AbeINTWC (ORCPT ); Fri, 14 Sep 2018 15:22:02 -0400 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w8EE4QwT085393 for ; Fri, 14 Sep 2018 10:07:21 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0a-001b2d01.pphosted.com with ESMTP id 2mgd2jce6s-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 14 Sep 2018 10:07:21 -0400 Received: from localhost by e06smtp05.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 14 Sep 2018 15:07:16 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w8EE7FQM66125872 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Fri, 14 Sep 2018 14:07:15 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1A5534C046; Fri, 14 Sep 2018 17:07:06 +0100 (BST) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BDE6B4C040; Fri, 14 Sep 2018 17:07:05 +0100 (BST) Received: from mschwideX1 (unknown [9.152.212.164]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 14 Sep 2018 17:07:05 +0100 (BST) Date: Fri, 14 Sep 2018 16:07:14 +0200 From: Martin Schwidefsky To: Peter Zijlstra Cc: will.deacon@arm.com, aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, npiggin@gmail.com, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux@armlinux.org.uk, heiko.carstens@de.ibm.com, Linus Torvalds Subject: Re: [RFC][PATCH 01/11] asm-generic/tlb: Provide a comment In-Reply-To: <20180914130207.GD24106@hirez.programming.kicks-ass.net> References: <20180913092110.817204997@infradead.org> <20180913092811.894806629@infradead.org> <20180913123014.0d9321b8@mschwideX1> <20180913105738.GW24124@hirez.programming.kicks-ass.net> <20180913141827.1776985e@mschwideX1> <20180913123937.GX24124@hirez.programming.kicks-ass.net> <20180914122824.181d9778@mschwideX1> <20180914130207.GD24106@hirez.programming.kicks-ass.net> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-TM-AS-GCONF: 00 x-cbid: 18091414-0020-0000-0000-000002C659ED X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18091414-0021-0000-0000-00002113BCAE Message-Id: <20180914160714.45a11f13@mschwideX1> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-09-14_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 lowpriorityscore=0 mlxlogscore=737 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809140147 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 14 Sep 2018 15:02:07 +0200 Peter Zijlstra wrote: > On Fri, Sep 14, 2018 at 12:28:24PM +0200, Martin Schwidefsky wrote: > > > I spent some time to get s390 converted to the common mmu_gather code. > > There is one thing I would like to request, namely the ability to > > disable the page gather part of mmu_gather. For my prototype patch > > see below, it defines the negative HAVE_RCU_NO_GATHER_PAGES Kconfig > > symbol that if defined will remove some parts from common code. > > Ugly but good enough for the prototype to convey the idea. > > For the final solution we better use a positive Kconfig symbol and > > add that to all arch Kconfig files except for s390. > > In a private thread ealier Linus raised the point that the batching and > freeing of lots of pages at once is probably better for I$. That would be something to try. For now I would like to do a conversion that more or less preserves the old behavior. You know these pesky TLB related bugs.. > > +config HAVE_RCU_NO_GATHER_PAGES > > + bool > > I have a problem with the name more than anything else; this name > suggests it is the RCU table freeing that should not batch, which is not > the case, you want the regular page gather gone, but very much require > the RCU table gather to batch. > > So I would like to propose calling it: > > config HAVE_MMU_GATHER_NO_GATHER > > Or something along those lines. Imho a positive config option like HAVE_MMU_GATHER_PAGES would make the most sense. It has the downside that it needs to be added to all arch/*/Kconfig files except for s390. But I am not hung-up on a name, whatever does not sound to awful will do for me. HAVE_MMU_GATHER_NO_GATHER would be ok. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.