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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8578ECCA481 for ; Mon, 11 Jul 2022 13:35:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229726AbiGKNfM (ORCPT ); Mon, 11 Jul 2022 09:35:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35560 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229767AbiGKNfK (ORCPT ); Mon, 11 Jul 2022 09:35:10 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89FD131DF5; Mon, 11 Jul 2022 06:35:09 -0700 (PDT) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4LhPvr4LMyzkWtj; Mon, 11 Jul 2022 21:32:56 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 11 Jul 2022 21:35:05 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 11 Jul 2022 21:35:04 +0800 Message-ID: <13b283fe-10f7-376f-9b8e-856e4d1e0ede@huawei.com> Date: Mon, 11 Jul 2022 21:35:04 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 2/4] mm: rmap: Allow platforms without mm_cpumask to defer TLB flush Content-Language: en-US To: Barry Song <21cnbao@gmail.com>, , , , , , , CC: , , , , , , , , , , , , , , , Barry Song References: <20220711034615.482895-1-21cnbao@gmail.com> <20220711034615.482895-3-21cnbao@gmail.com> From: Kefeng Wang In-Reply-To: <20220711034615.482895-3-21cnbao@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org Hi Barry， On 2022/7/11 11:46, Barry Song wrote: > From: Barry Song > > Platforms like ARM64 have hareware TLB shootdown broadcast. They > don't maintain mm_cpumask but just send tlbi and related sync > instructions for TLB flush. task's mm_cpumask is normally empty > in this case. We also allow deferred TLB flush on this kind of > platforms. > > Signed-off-by: Barry Song > > --- ... > diff --git a/mm/Kconfig b/mm/Kconfig > index 169e64192e48..7bf54f57ca01 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -951,6 +951,9 @@ config ARCH_HAS_CURRENT_STACK_POINTER > register alias named "current_stack_pointer", this config can be > selected. > > +config ARCH_HAS_MM_CPUMASK > + bool > + > config ARCH_HAS_VM_GET_PAGE_PROT > bool > > diff --git a/mm/rmap.c b/mm/rmap.c > index 5bcb334cd6f2..13d4f9a1d4f1 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -692,6 +692,10 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) > if (!(flags & TTU_BATCH_FLUSH)) > return false; > > +#ifndef CONFIG_ARCH_HAS_MM_CPUMASK > + return true; > +#endif > + Here is another option to enable arch's tlbbatch defer [1] https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20171101101735.2318-2-khandual@linux.vnet.ibm.com/ > /* If remote CPUs need to be flushed then defer batch the flush */ > if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids) > should_defer = true;