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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=huznAKYddU0oZFKAUlCcQ1STeT/7wXvr3I03BhqGvib3xpajTRxhfLH9R4n0xbL3S kIEIw7UozOwAKAYis3taxahTMvipmp7uuojl2U657r8N7zaBJ5NTsf4aP8uJ8+p+Rb BYYgwF3ME4VdyiRufVFi72RJCpQxDxT6c94/F8TA= Date: Mon, 5 Oct 2026 12:07:46 +0100 From: Catalin Marinas To: Zi Yan Cc: Kristina =?utf-8?Q?Mart=C5=A1enko?= , linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, kvmarm@lists.linux.dev, linux-efi@vger.kernel.org, Will Deacon , Mark Rutland , Ryan Roberts , David Hildenbrand , Lorenzo Stoakes , Linu Cherian , Anshuman Khandual , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Ard Biesheuvel , Ilias Apalodimas , linux-mm@kvack.org Subject: Re: [RFC 00/12] arm64: Add support for TLBI domains Message-ID: References: <20261001110655.461473-1-kristina.martsenko@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: eohm98ng6cy4668sm7ndghjkctaspah4 X-Rspam-User: X-Rspamd-Queue-Id: 27CFCA000C X-Rspamd-Server: rspam08 X-HE-Tag: 1791198474-327743 X-HE-Meta: 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 L1Tgj2zt qrSsHrfL7lSjgx9rd1gaMQnOX6ARq+oFVcvYzg6tjEdaY0v10nRfLZ6glshj22x2VfIdSgp3NxaaSW+zFdMe8b9jQ2UPL9FLaAPCO4vfz8KGjlZWSASrsI0AGRqwkUmeXB5qtvtKde5vNTswesObvlgCYoHOSsq9sYp5KH3BYU1BqIdlDi1L69+qPiQkykY06KeauwXKopI8dF66SgGSLDsQn58evXZc/lCDZvHS8bCyzCDvZ63q/LY1QvIs1lavZtlMr Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Oct 04, 2026 at 02:06:48PM -0400, Zi Yan wrote: > On Thu Oct 1, 2026 at 7:06 AM EDT, Kristina Martšenko wrote: > > This series allows the kernel to use TLBI domains. TLBI domains (FEAT_TLBID) is > > an Arm architecture feature that enables a TLB invalidation to target a subset > > of CPUs instead of the whole system. It can improve performance on systems with > > many CPUs. TLBID is not yet part of the Arm Architecture Reference Manual but > > some of it is described in the latest XML [1]. > > > > The goal of this series is to send TLBI commands only to the CPUs where a > > process has run (i.e. where its page tables have been installed). The last > > IIUC, mm_cpumask() is used to store this information on x86 and other > archs. I see you put this information in tlbid_domains of mm_context_t > from patch 9, although in the form of tlb id domains. I wonder why not > make arm64 also update mm_cpumask() like x86 and other archs and derive > the tlbid domains based on mm_cpumask() and a cpu-to-domain mapping > (added in patch 7). One reason is that it's cheaper to compute the tlbi domains at context switch time (bitmap-and IIRC) than working from mm_cpumask() every time we do a TLBI. That said, suggestions for a quick algorithm are welcome. Subject to the race conditions Will mentioned, we could use the mm_cpumask() for a quick check if we ever ran on that CPU and avoid recomputing the tlbi domains. -- Catalin