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Tue, 27 Sep 2022 06:16:52 +0000 (UTC) X-FDA: 79956857064.03.D367196 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf14.hostedemail.com (Postfix) with ESMTP id 9D48B100002 for ; Tue, 27 Sep 2022 06:16:51 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4E1121042; Mon, 26 Sep 2022 23:16:57 -0700 (PDT) Received: from [10.162.41.7] (unknown [10.162.41.7]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9FBDD3F73B; Mon, 26 Sep 2022 23:16:41 -0700 (PDT) Message-ID: <168eac93-a6ee-0b2e-12bb-4222eff24561@arm.com> Date: Tue, 27 Sep 2022 11:46:38 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v4 2/2] arm64: support batched/deferred tlb shootdown during page reclamation Content-Language: en-US To: Yicong Yang , akpm@linux-foundation.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-doc@vger.kernel.org Cc: corbet@lwn.net, peterz@infradead.org, arnd@arndb.de, linux-kernel@vger.kernel.org, darren@os.amperecomputing.com, yangyicong@hisilicon.com, huzhanyuan@oppo.com, lipeifeng@oppo.com, zhangshiming@oppo.com, guojian@oppo.com, realmz6@gmail.com, 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 <21cnbao@gmail.com>, wangkefeng.wang@huawei.com, xhao@linux.alibaba.com, prime.zeng@hisilicon.com, Barry Song , Nadav Amit , Mel Gorman References: <20220921084302.43631-1-yangyicong@huawei.com> <20220921084302.43631-3-yangyicong@huawei.com> From: Anshuman Khandual In-Reply-To: <20220921084302.43631-3-yangyicong@huawei.com> Content-Type: text/plain; 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dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf14.hostedemail.com: domain of anshuman.khandual@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=anshuman.khandual@arm.com X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 9D48B100002 X-Stat-Signature: qjksb5hipe1as6x1s9wttae16wpnuc3m X-HE-Tag: 1664259411-582531 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 9/21/22 14:13, Yicong Yang wrote: > +static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm) > +{ > + /* for small systems with small number of CPUs, TLB shootdown is cheap */ > + if (num_online_cpus() <= 4) It would be great to have some more inputs from others, whether 4 (which should to be codified into a macro e.g ARM64_NR_CPU_DEFERRED_TLB, or something similar) is optimal for an wide range of arm64 platforms. > + return false;> + > +#ifdef CONFIG_ARM64_WORKAROUND_REPEAT_TLBI > + if (unlikely(this_cpu_has_cap(ARM64_WORKAROUND_REPEAT_TLBI))) > + return false; > +#endif > + > + return true; > +} > + [...]