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d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=i2JP/AK/462flQNf3WkuAKr99hiwoo70NGIBG6Typ3w=; b=2mxsnqfiIUXQmaExq0k9MLRS9m86nIyc/ZZPBmac0QM0LR1CuFFHL8dQpBL6YELTt5 2Z/bcoEOSrvp2PQ3S8emqhpJZB2Ru/lULqd01trSX8+UhCRTisqs5177pPq55VF8I9nD pm5nANfQb+r9jJNpshkvZsHR2ZdM6OmkUtWvVAc45zbSnKBmHfReJCwyPZf3fJ4ZqQr+ 9GIYyHgjkPw+HBG1t6MPTVt6gruaoaUf0p1pI1pSGii929pukGSkxgRv9VwORG4LccAO IKuICIJZbW1JfI8yOvJTm3l423vZk2B5aLWk/XbKPsgv9HWhhiF4EgEqFnddA4SFw7LV mVVg== X-Gm-Message-State: AJIora9am2pmpyJFiM5tH0MnpYYB6SmFt/TAFdSX00vDQe7Yk5HjWtzz 9NcpPLjl6qD1t2JHMbLf0tK+2jMn0GA0zVoofj4= X-Google-Smtp-Source: AGRyM1u3B9GaqsJzc2ZnGgAx20N9pPna/H/YyY3hApLIj/mDA7Feo0MOU0K0s1MJSpzYriYuHv0RZqEbB9CZJ8ZQIzU= X-Received: by 2002:a17:906:8a45:b0:72b:31d4:d537 with SMTP id gx5-20020a1709068a4500b0072b31d4d537mr17046686ejc.170.1657579957647; Mon, 11 Jul 2022 15:52:37 -0700 (PDT) MIME-Version: 1.0 References: <20220711034615.482895-1-21cnbao@gmail.com> <20220711034615.482895-3-21cnbao@gmail.com> <13b283fe-10f7-376f-9b8e-856e4d1e0ede@huawei.com> In-Reply-To: <13b283fe-10f7-376f-9b8e-856e4d1e0ede@huawei.com> From: Barry Song <21cnbao@gmail.com> Date: Tue, 12 Jul 2022 10:52:24 +1200 Message-ID: Subject: Re: [PATCH v2 2/4] mm: rmap: Allow platforms without mm_cpumask to defer TLB flush To: Kefeng Wang Cc: Andrew Morton , Linux-MM , LAK , x86 , Catalin Marinas , Will Deacon , Linux Doc Mailing List , Jonathan Corbet , Arnd Bergmann , LKML , Darren Hart , Yicong Yang , huzhanyuan@oppo.com, =?UTF-8?B?5p2O5Z+56ZSLKHdpbmsp?= , =?UTF-8?B?5byg6K+X5piOKFNpbW9uIFpoYW5nKQ==?= , =?UTF-8?B?6YOt5YGl?= , real mz , linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, Barry Song Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1657579959; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=i2JP/AK/462flQNf3WkuAKr99hiwoo70NGIBG6Typ3w=; b=aW8CIu45/yJjMQACDoGR2KuefiJWGxmMN2Pj/zOp/FguHLnH/OkkdpQf1HWUSSujcgidQ9 GgqKxdiq/ts2UXhyIg/PefTmw4epN/GE1pkq7hTZ9TPDrBPsB/RuXKSsFGDiar2/Z7rWAN ZoyeMXO0TsC7sWxHQoPdcBKqcduhwCU= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=ErppBv82; spf=pass (imf15.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.218.45 as permitted sender) smtp.mailfrom=21cnbao@gmail.com; dmarc=pass (policy=none) header.from=gmail.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1657579959; a=rsa-sha256; cv=none; b=wZwuEwG9U9PXrERXRATff2ODlioYlza/IN2F9ZrLw5It+9qw4iY2OzjBspbREb8H1zU/8B or63aFiRrTPxyVl2dGnoHEMqB2v9ksxDjSuQwUSXTC9b2grruA5wmqrmZ0rAkwOVEzCCPG Lf/ygv++18m1hhAJOPa2nmdYrVhyU7c= X-Rspamd-Server: rspam02 X-Stat-Signature: x184d119kmoena47thrxbe9qgospoyuc X-Rspamd-Queue-Id: EB008A0059 X-Rspam-User: Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=ErppBv82; spf=pass (imf15.hostedemail.com: domain of 21cnbao@gmail.com designates 209.85.218.45 as permitted sender) smtp.mailfrom=21cnbao@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1657579958-659664 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Jul 12, 2022 at 1:35 AM Kefeng Wang wr= ote: > > Hi Barry=EF=BC=8C > > 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 b= e > > 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 *m= m, 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 > This option is even better than simply having ARCH_HAS_MM_CPUMASK since arch might make decisions based on specific hardware characters. for example, https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-November/165468.html +bool arch_tlbbatch_should_defer(struct mm_struct *mm) +{ + if (!radix_enabled() || cpu_has_feature(CPU_FTR_POWER9_DD1)) + return false; + + if (!mm_is_thread_local(mm)) + return true; + + return false; +} In this case, having MM_CPUMASK doesn't necessarily mean tlbbatch is needed= . > [1] > https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20171101101735.23= 18-2-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 =3D true; Thanks Barry