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Thu, 27 Nov 2025 06:11:44 -0800 (PST) Received: from J9GPGXL7NT.bytedance.net ([61.213.176.58]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3477b7341d2sm2030249a91.11.2025.11.27.06.11.39 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 27 Nov 2025 06:11:44 -0800 (PST) From: Xu Lu To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, kees@kernel.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, akpm@linux-foundation.org, david@redhat.com, apatel@ventanamicro.com, guoren@kernel.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Xu Lu Subject: [RFC PATCH v2 1/9] riscv: Introduce RISCV_LAZY_TLB_FLUSH config Date: Thu, 27 Nov 2025 22:11:09 +0800 Message-ID: <20251127141117.87420-2-luxu.kernel@bytedance.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20251127141117.87420-1-luxu.kernel@bytedance.com> References: <20251127141117.87420-1-luxu.kernel@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 4A4A540017 X-Stat-Signature: kirgpwbdy4nfafg1j7bea1qu7b97mqxd X-Rspam-User: X-HE-Tag: 1764252706-36114 X-HE-Meta: U2FsdGVkX19+T7/pwsxQmGQD0wDO+zIsKId+TN+WbfK887Fwc1j1gggJMRLZB03BRplNb9kCJ655KneIkrOEXC1Em+onHR+zs5LIP2oOcnMKfz0ZVXDnNalHw1o4DzCTzcAabqnfFehqxGJJtcBBT8HqBSyfeEXEbN22as82+0yYCCNd/GIbVQbL3/pggTjovRvrC4iWwezBwlJ6PCS2drjShfN8PoVeb5RwEwx0vr4oXv7YMdkjR8K4TeeMOa+WqUmDVcHbVpKDvVooLFumGnD60T/DO4KtWpKg8fziwqe8Cnz34N3OInw8HAzfXTB1DBJ9zB35h/l2hJdTKZYO1/X8E9Di1xgO42vrHY/ksjOP7XxOLk3r1inCa1q1pQY5TYaiJOayU8qLTPKvMMxcg3BXQJy6yiTYgVdVjPeFfbirJFmS1UWJIk9x17J4Z/KonHiyypSC7KoL0Ip76E4RFGcpjIT8Wa6KYuta5Qn3Dk3v7q5S5tSrXxah8uf2L2vaDbua2Uar8hPYNqwU0YUYXPbLEOoFLZlBsxDAyuxTJm0kkUE6cj0tcH6Hof5uwHJ9j2kLX9zXSpw9YAK3uvf5zBkRHUzfEtpxemrf8RVBVJD2K1YXa4CRv5FhmvuvcMLytcoeH1WGVs34nyx9uc+xEWmdRVcyXp2KWrf+shkEjU7APNtghp7VFE8s1x54BhTUMHiRyyil8MmfIke9iQegiF8t6hCtW5l5L3iwbz3AJTd312B2xLNShIe+hvzSBu9R/wug3XkgzbouDTbyS45uX4bCdewJRTEkpMWPzC9PKxMV9mZEnUiwU/+az6ssmr7pHV3lGu1qzxAhAMNokj0Dp4H2KQygH/nqGrEALv5GUZFVYWC4ELqXiotj0huL/+aj6B0bmLfq0eID9Q1rF9GQ4PpO5hkQOZD34HJvSAJNQcGLlmi020dk2HmxbG1/zKAu3JgQo/awGxsgrjiJFP/ 1svpHsAC eAFNP0AUu68KAFsDs8n+x6wlE+3ISJH13jon9oJA3Mf11IADGXvJWCHoYmeuqsQL7lLI0Zg7FB1c2HeL3hdRGH50C3DmnB0OHQxR6jeU7q6XTM8bC8oUA9uukfzaPum3QGCVAadCXSWMOjItIG43IBuVsuQeAnlPObZDZaFras8dNdofQO6+/ekUx3u9LUwtLxk95NMLBuoIxCkdufO62+djUcRjMxxi4eX9aA4gsHIxYaJjKj2ycamqPgOkMT7FTTZ3XnQTotWerync6iW1JT1ntXO7ppNcCNLOYiWEYBjC/ZE8L7G0A1xtAkgYsD/9NMYCO+eLdTZ7Z/TbWwYl2UW051hFRdpQbjmIcmVISCFOtBus= 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: List-Subscribe: List-Unsubscribe: This feature avoids unnecessary TLB Flush IPIs. After memory mapping modifications on certain mm_struct, instead of sending IPIs, this feature records the TLB Flush information on percpu buffer, defer the TLB Flush to the moment when target CPUs really load this mm_struct. Signed-off-by: Xu Lu --- arch/riscv/Kconfig | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 22cda9c452d2a..d219c7f4b129e 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -925,6 +925,18 @@ config RISCV_VECTOR_MISALIGNED help Enable detecting support for vector misaligned loads and stores. +config RISCV_LAZY_TLB_FLUSH + bool "Defer TLB Flush to context switch to avoid IPIs" + depends on MMU && SMP + def_bool n + help + This feature avoids unnecessary TLB Flush IPIs. After memory mapping + modifications on certain mm_struct, instead of sending IPIs, this feature + records the TLB Flush information on percpu buffer, defer the TLB Flush + to the moment when target CPUs really load this mm_struct. + + If unsure what to do here, say N. + choice prompt "Unaligned Accesses Support" default RISCV_PROBE_UNALIGNED_ACCESS -- 2.20.1