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GET /api/1.2/patches/2219873/?format=api
{ "id": 2219873, "url": "http://patchwork.ozlabs.org/api/1.2/patches/2219873/?format=api", "web_url": "http://patchwork.ozlabs.org/project/glibc/patch/20260405035323.558335-5-wangrui@loongson.cn/", "project": { "id": 41, "url": "http://patchwork.ozlabs.org/api/1.2/projects/41/?format=api", "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": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260405035323.558335-5-wangrui@loongson.cn>", "list_archive_url": null, "date": "2026-04-05T03:53:20", "name": "[v8,4/6] 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/1.2/people/85150/?format=api", "name": "WANG Rui", "email": "wangrui@loongson.cn" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/glibc/patch/20260405035323.558335-5-wangrui@loongson.cn/mbox/", "series": [ { "id": 498763, "url": "http://patchwork.ozlabs.org/api/1.2/series/498763/?format=api", "web_url": "http://patchwork.ozlabs.org/project/glibc/list/?series=498763", "date": "2026-04-05T03:53:16", "name": "elf: THP-aware load segment alignment", "version": 8, "mbox": "http://patchwork.ozlabs.org/series/498763/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2219873/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2219873/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<libc-alpha-bounces~incoming=patchwork.ozlabs.org@sourceware.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "libc-alpha@sourceware.org" ], "Delivered-To": [ "patchwork-incoming@legolas.ozlabs.org", "libc-alpha@sourceware.org" ], "Authentication-Results": [ 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b=YmtC2uQb54WFnYJKNuU5KP/ByyyKsu0OtPDu0YssxDCuTI1QhhfXdV9bzPiao4QkGEHr9Qi+bxuNN84EHozQI5XgFwGV7UWQSLGu7cvkwzMwaM4xFqSKVlh5VwN6WItyUb7eHFw/IpgLdvMixwpMc7a2JK1rfxjljc4rDw2ic1U=", "ARC-Message-Signature": "i=1; a=rsa-sha256; d=sourceware.org; s=key;\n t=1775361256; c=relaxed/simple;\n bh=R6Yv29w4nzNxZJlsdjeV5hcaHovFXPv2WKsbGFl1ft0=;\n h=From:To:Subject:Date:Message-ID:MIME-Version;\n b=gpGktMyHzkNr59Wlf2WdEBxJ98XNpn84uswha8eijsLWPW9Uycxrvomhxkm3iSqQ7qGYa/uzVWMCCTHaO1ORrbCexaAj4HZx1ErWatzI7/rWzngCPD1hd8aiJkqJtq86jFlvo603QdkjbN8WgUaGiOEuwMShe75cq57Z3O1lYmE=", "ARC-Authentication-Results": "i=1; server2.sourceware.org", "From": "WANG Rui <wangrui@loongson.cn>", "To": "libc-alpha@sourceware.org", "Cc": "Adhemerval Zanella <adhemerval.zanella@linaro.org>,\n Dev Jain <dev.jain@arm.com>, Florian Weimer <fweimer@redhat.com>,\n Wilco Dijkstra <Wilco.Dijkstra@arm.com>, Xi Ruoyao <xry111@xry111.site>,\n WANG Xuerui <git@xen0n.name>, caiyinyu <caiyinyu@loongson.cn>,\n mengqinggang <mengqinggang@loongson.cn>,\n Huacai Chen <chenhuacai@kernel.org>, hjl.tools@gmail.com,\n WANG Rui <wangrui@loongson.cn>", "Subject": "[PATCH v8 4/6] tunables: Add glibc.elf.thp tunable for THP-aware\n segment alignment", "Date": "Sun, 5 Apr 2026 11:53:20 +0800", "Message-ID": "<20260405035323.558335-5-wangrui@loongson.cn>", "X-Mailer": "git-send-email 2.53.0", "In-Reply-To": "<20260405035323.558335-1-wangrui@loongson.cn>", "References": "<20260405035323.558335-1-wangrui@loongson.cn>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-CM-TRANSID": "qMiowJBxDOHK3NFpP1JlAA--.44692S6", "X-CM-SenderInfo": "pzdqw2txl6z05rqj20fqof0/", "X-Coremail-Antispam": "1Uk129KBj93XoWxCF4xKFyUZrW8ur15tw4UJrc_yoW5AFy3pr\n y3WFWYkr43AFnxCFWay3W5Aa15Jw4fKa4UGry7Kwn7Xw43Gryftay2gr47Jay7Jr47AF47\n ZrZFgr47Cw4kG3cCm3ZEXasCq-sJn29KB7ZKAUJUUUU7529EdanIXcx71UUUUU7KY7ZEXa\n sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU\n 0xBIdaVrnRJUUUBYb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2\n IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v\n e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI\n 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_\n Gr0_Gr1UM2kKe7AKxVWUXVWUAwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07AIYI\n kI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWrXVW3\n AwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcxkI7VAKI4\n 8JMxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j\n 6r4UMxCIbckI1I0E14v26r1Y6r17MI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwV\n AFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv2\n 0xvE14v26ryj6F1UMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4\n v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_Cr1lIxAIcVC2z280aVCY1x0267AK\n xVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IUneRRtUUUUU==", "X-BeenThere": "libc-alpha@sourceware.org", "X-Mailman-Version": "2.1.30", "Precedence": "list", "List-Id": "Libc-alpha mailing list <libc-alpha.sourceware.org>", "List-Unsubscribe": "<https://sourceware.org/mailman/options/libc-alpha>,\n <mailto:libc-alpha-request@sourceware.org?subject=unsubscribe>", "List-Archive": "<https://sourceware.org/pipermail/libc-alpha/>", "List-Post": "<mailto:libc-alpha@sourceware.org>", "List-Help": "<mailto:libc-alpha-request@sourceware.org?subject=help>", "List-Subscribe": "<https://sourceware.org/mailman/listinfo/libc-alpha>,\n <mailto:libc-alpha-request@sourceware.org?subject=subscribe>", "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 <Wilco.Dijkstra@arm.com>\nSigned-off-by: WANG Rui <wangrui@loongson.cn>\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 72769428e8c..389690d840b 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": [ "v8", "4/6" ] }