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b=gFHs0RI0vQiYN70xLjJK6AIYAhKscdvLrr5shld7PhX2KZychrY1pspfUyGMIyjgR mbkFt9Cb7WMu6rmV0YK7D6FB1RqQpIwcnjbvH/a8zwzdISBXeDxfcPXSds6DBbys25 UPDLmNmI5IR8DhAvnAxyD7B0lABLUqOm8rN5+XVq/cKEJprw7em17Xe35a7kBMxQnj 2nIkE+qQq91I2LBKt5owi+zYqepp7uqZU1R5dNPMIPeduKfGwHtf9JvyuvaHBtbPLX oSWkiCiwB41mvjZxskSm+7HDZWrGWb6aVcllIiebe2luvrsOd4VQUN7q9UO4HkfmtL EZb5je/2vyG6w== Date: Mon, 5 Oct 2026 07:29:51 +0100 From: Will Deacon 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, Catalin Marinas , 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-Rspamd-Server: rspam06 X-Stat-Signature: kr6nkppax1f1rfzi9757jnb9da7i9dfy X-Rspam-User: X-Rspamd-Queue-Id: 4F782C0002 X-HE-Tag: 1791181801-937802 X-HE-Meta: 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 bwqU8v4n RPFymlfpdXqrRv9dj1S/lG2Bo7HcYdVZTFBYE0PDYjDWHYTT30zB2elScaQqjieGiGEaVi3HOiCOIon6y1vzkubR5O2NrpQTCL5Gmj2kNZ3TORRp0b2XekFV2U+s5WphB5cr2A8UYO50Hu9Njx2+wrUXYRrZ5MYjPXjwyEMkpyGZlis0j4JANjnzEHDC4LTZhZNzsl77MogKDurf567zCHP0zNc923w97MJuh0StwYjcMG+5+9LT8Lk9j2JelviLbSFCOKAifI27LDV8eFreR8Zs0jg== 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). Historically, maintaining mm_cpumask() was a horrible source of contention when we looked at it in the past. Maybe that's no longer true, but it would be good to see some numbers if we want to start keeping that thing accurate on arm64. Will