From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Schwidefsky Subject: Re: [RFC][PATCH 01/11] asm-generic/tlb: Provide a comment Date: Fri, 14 Sep 2018 16:07:14 +0200 Message-ID: <20180914160714.45a11f13@mschwideX1> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180914130207.GD24106@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org 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 List-Id: linux-arch.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. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:58810 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726908AbeINTWC (ORCPT ); Fri, 14 Sep 2018 15:22:02 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w8EE47mw056112 for ; Fri, 14 Sep 2018 10:07:21 -0400 Received: from e06smtp05.uk.ibm.com (e06smtp05.uk.ibm.com [195.75.94.101]) by mx0b-001b2d01.pphosted.com with ESMTP id 2mge7brvva-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! Violators will be prosecuted for from ; Fri, 14 Sep 2018 15:07:19 +0100 Date: Fri, 14 Sep 2018 16:07:14 +0200 From: Martin Schwidefsky 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> MIME-Version: 1.0 Message-ID: <20180914160714.45a11f13@mschwideX1> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: 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 Message-ID: <20180914140714.v7bKLr2iGFVMqlksud91QljtOp3UipR19dMZVCLle5w@z> 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.