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[181.162.63.237]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-72dab9c8d2bsm7809544b3a.92.2025.01.20.12.42.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jan 2025 12:42:39 -0800 (PST) From: =?utf-8?q?Cristian_Rodr=C3=ADguez?= To: libc-alpha@sourceware.org Cc: =?utf-8?q?Cristian_Rodr=C3=ADguez?= Subject: [PATCH] Document glibc.pthread.stack_hugetlb does nothing in recent kernels Date: Mon, 20 Jan 2025 17:42:29 -0300 Message-ID: <20250120204233.12181-1-cristian@rodriguez.im> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 X-Spam-Status: No, score=-10.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, GIT_PATCH_0, HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libc-alpha-bounces~patchwork=sourceware.org@sourceware.org Since c4608d1bf7c: mm: mmap: map MAP_STACK to VM_NOHUGEPAGE All MAP_STACK allocations imply NOHUGEPAGE and the tunable does nothing. Signed-off-by: Cristian Rodríguez --- manual/tunables.texi | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/manual/tunables.texi b/manual/tunables.texi index 7f0246c789..468432fc57 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -509,6 +509,10 @@ its value to @code{0} enables the use of @code{madvise} with This is a memory utilization optimization, since internal glibc setup of either the thread descriptor and the guard page might force the kernel to move the thread stack originally backup by Huge Pages to default pages. + +This tunable has no effect on the linux kernel version 6.7 +or later where MADV_NOHUGEPAGE is the default for stack mappings. + @end deftp @node Hardware Capability Tunables