{"id":2222548,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2222548/?format=json","web_url":"http://patchwork.ozlabs.org/project/glibc/patch/20260412174334.3111385-4-wangrui@loongson.cn/","project":{"id":41,"url":"http://patchwork.ozlabs.org/api/1.1/projects/41/?format=json","name":"GNU C Library","link_name":"glibc","list_id":"libc-alpha.sourceware.org","list_email":"libc-alpha@sourceware.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260412174334.3111385-4-wangrui@loongson.cn>","date":"2026-04-12T17:43:31","name":"[v9,3/6] tunables: Add glibc.elf.thp tunable for THP-aware segment alignment","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"f25a5a9b8e909c0e0daf4bcfe0fc17b6f64e4f38","submitter":{"id":85150,"url":"http://patchwork.ozlabs.org/api/1.1/people/85150/?format=json","name":"WANG Rui","email":"wangrui@loongson.cn"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/glibc/patch/20260412174334.3111385-4-wangrui@loongson.cn/mbox/","series":[{"id":499622,"url":"http://patchwork.ozlabs.org/api/1.1/series/499622/?format=json","web_url":"http://patchwork.ozlabs.org/project/glibc/list/?series=499622","date":"2026-04-12T17:43:29","name":"elf: THP-aware load segment alignment","version":9,"mbox":"http://patchwork.ozlabs.org/series/499622/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2222548/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2222548/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":["incoming@patchwork.ozlabs.org","libc-alpha@sourceware.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","libc-alpha@sourceware.org"],"Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=sourceware.org\n (client-ip=38.145.34.32; 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a=rsa-sha256; d=sourceware.org; s=key; t=1776015865; cv=none;\n b=HfW9PPuAjmzBWlvysNaQ72CsFbi0K2spncP5GTw9qlwVdg0FZBRuv9M7WIdNusY545RTGrHQSpiickt37yauz/te2NlV6PakXHrZCZIg9tw/rxSvJ/Y7k8fJBsyw42XFbSWVs8Vi5XO5NpLGuxsrGSqdiIHwg5gpvJ7+AnIqjXo=","ARC-Message-Signature":"i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1776015865; c=relaxed/simple;\n bh=pzIBm5MZkSbBPCe+NFOSDcYU9IEqfnEQwbfbSm8EllM=;\n h=From:To:Subject:Date:Message-ID:MIME-Version;\n b=PQWTBJxzZ1MfSLBjlx/v9jyFkrrcRPvvoiMVYF1biZPMtHcI8Tj4EC+fqcLD8j0li6g5bur1Pky5tmwiYK2Dtr3frsllu/qfY49AGXF+wxjHbGHKerXRwpOpIycPyHproSwa0/EsU3w1lN09LQs0w0zYK64T/KLXZOYt/OQE1LQ=","ARC-Authentication-Results":"i=1; server2.sourceware.org","From":"WANG Rui ","To":"libc-alpha@sourceware.org","Cc":"Adhemerval Zanella ,\n Dev Jain , Florian Weimer ,\n Wilco Dijkstra , Xi Ruoyao ,\n WANG Xuerui , caiyinyu ,\n mengqinggang ,\n Huacai Chen , hjl.tools@gmail.com,\n WANG Rui ","Subject":"[PATCH v9 3/6] tunables: Add glibc.elf.thp tunable for THP-aware\n segment alignment","Date":"Mon, 13 Apr 2026 01:43:31 +0800","Message-ID":"<20260412174334.3111385-4-wangrui@loongson.cn>","X-Mailer":"git-send-email 2.53.0","In-Reply-To":"<20260412174334.3111385-1-wangrui@loongson.cn>","References":"<20260412174334.3111385-1-wangrui@loongson.cn>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-CM-TRANSID":"qMiowJBxrsLo2dtpo51rAA--.49052S2","X-CM-SenderInfo":"pzdqw2txl6z05rqj20fqof0/","X-Coremail-Antispam":"1Uk129KBj93XoWxCF4xKFyUZrW8ur15tw4UJrc_yoW5AFy3pr\n y3WFWYkrW3AFnxCryay3W5Aa15Jws3Ka4UGry7Kwn7Xw45Cryftay2gr47Ja9rJr47AF47\n ZrZFgr47Cw4kG3cCm3ZEXasCq-sJn29KB7ZKAUJUUUU7529EdanIXcx71UUUUU7KY7ZEXa\n sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU\n 0xBIdaVrnRJUUUBIb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2\n IYs7xG6rWj6s0DM7CIcVAFz4kK6r126r13M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v\n e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI\n 0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv6xkF7I0E14v2\n 6r4j6r4UJwAaw2AFwI0_Jrv_JF1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqjxCEc2xF0c\n Ia020Ex4CE44I27wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E2Ix0cI8IcVAFwI0_Wrv_\n ZF1lYx0Ex4A2jsIE14v26F4j6r4UJwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64\n vIr41lc7CjxVAaw2AFwI0_JF0_Jw1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_\n Jr0_Gr1l4IxYO2xFxVAFwI0_Jrv_JF1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8Gjc\n xK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0\n cI8IcVAFwI0_Ar0_tr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26F4j6r4UJwCI42IY6xAIw2\n 0EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x02\n 67AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU02Nt7UUUUU==","X-BeenThere":"libc-alpha@sourceware.org","X-Mailman-Version":"2.1.30","Precedence":"list","List-Id":"Libc-alpha mailing list ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Errors-To":"libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org"},"content":"Introduce a new tunable, `glibc.elf.thp`, to control Transparent Huge\nPage (THP) aware alignment of ELF loadable segments.\n\nWhen set to `1`, the dynamic loader will attempt to align sufficiently\nlarge `PT_LOAD` segments to the PMD huge page size when mapping them.\nThis increases the likelihood that the kernel backs these mappings with\nTransparent Huge Pages.\n\nThe default value is `0`, which preserves the traditional page-sized\nalignment and keeps existing behavior unchanged.\n\nOn systems without THP support, or when THP is disabled in the kernel,\nenabling this tunable has no effect.\n\nReviewed-by: Wilco Dijkstra \nSigned-off-by: WANG Rui \n---\n elf/dl-tunables.list | 8 ++++++++\n manual/tunables.texi | 24 ++++++++++++++++++++++++\n 2 files changed, 32 insertions(+)","diff":"diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list\nindex 040a544c0e0..1bbf70d36fa 100644\n--- a/elf/dl-tunables.list\n+++ b/elf/dl-tunables.list\n@@ -24,6 +24,14 @@\n # env_alias: An alias environment variable\n \n glibc {\n+ elf {\n+ thp {\n+ type: INT_32\n+ minval: 0\n+ maxval: 1\n+ }\n+ }\n+\n malloc {\n check {\n type: INT_32\ndiff --git a/manual/tunables.texi b/manual/tunables.texi\nindex cb6a83754b0..12b515c628f 100644\n--- a/manual/tunables.texi\n+++ b/manual/tunables.texi\n@@ -64,6 +64,7 @@ glibc.pthread.mutex_spin_count: 100 (min: 0, max: 32767)\n glibc.rtld.optional_static_tls: 0x200 (min: 0x0, max: 0xffffffffffffffff)\n glibc.malloc.tcache_max: 0x0 (min: 0x0, max: 0xffffffffffffffff)\n glibc.malloc.check: 0 (min: 0, max: 3)\n+glibc.elf.thp: 0 (min: 0, max: 1)\n @end example\n \n @menu\n@@ -77,6 +78,8 @@ glibc.malloc.check: 0 (min: 0, max: 3)\n \t\t\t @theglibc{}.\n * gmon Tunables:: Tunables that control the gmon profiler, used in\n conjunction with gprof\n+* ELF Tunables:: Tunables that control Transparent Huge Page (THP)\n+ aware alignment of ELF loadable segments\n \n @end menu\n \n@@ -763,3 +766,24 @@ whose size exceeds the available memory; in that case, an out of memory\n error will be printed at program startup, the profiler will be\n disabled, and no @file{gmon.out} file will be generated.\n @end deftp\n+\n+@node ELF Tunables\n+@section ELF Tunables\n+@cindex elf tunables\n+\n+@deftp Tunable glibc.elf.thp\n+This tunable controls Transparent Huge Page (THP) aware alignment of\n+ELF loadable segments.\n+\n+The default value is @code{0}, which preserves the traditional page-sized\n+alignment for loadable segments.\n+\n+If set to @code{1}, glibc will attempt to align sufficiently large\n+@code{PT_LOAD} segments to the PMD huge page size when mapping them\n+with @code{mmap}. This increases the likelihood that the kernel can\n+back these mappings with Transparent Huge Pages.\n+\n+This tunable has an effect only on systems that support Transparent\n+Huge Pages (currently Linux). On other systems, or if THP is disabled\n+at the kernel level, enabling this tunable has no effect.\n+@end deftp\n","prefixes":["v9","3/6"]}