{"id":2222544,"url":"http://patchwork.ozlabs.org/api/1.2/covers/2222544/?format=json","web_url":"http://patchwork.ozlabs.org/project/glibc/cover/20260412174334.3111385-1-wangrui@loongson.cn/","project":{"id":41,"url":"http://patchwork.ozlabs.org/api/1.2/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":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260412174334.3111385-1-wangrui@loongson.cn>","list_archive_url":null,"date":"2026-04-12T17:43:28","name":"[v9,0/6] elf: THP-aware load segment alignment","submitter":{"id":85150,"url":"http://patchwork.ozlabs.org/api/1.2/people/85150/?format=json","name":"WANG Rui","email":"wangrui@loongson.cn"},"mbox":"http://patchwork.ozlabs.org/project/glibc/cover/20260412174334.3111385-1-wangrui@loongson.cn/mbox/","series":[{"id":499622,"url":"http://patchwork.ozlabs.org/api/1.2/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/covers/2222544/comments/","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=2620:52:6:3111::32; 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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 0/6] elf: THP-aware load segment alignment","Date":"Mon, 13 Apr 2026 01:43:28 +0800","Message-ID":"<20260412174334.3111385-1-wangrui@loongson.cn>","X-Mailer":"git-send-email 2.53.0","MIME-Version":"1.0","Content-Type":"text/plain; charset=UTF-8","Content-Transfer-Encoding":"8bit","X-CM-TRANSID":"qMiowJBxxuLT2dtpi51rAA--.48016S2","X-CM-SenderInfo":"pzdqw2txl6z05rqj20fqof0/","X-Coremail-Antispam":"1Uk129KBj93XoWxCw45Cw4furWrXF48Xr1DurX_yoWrKF18pF\n WSkFn5KFWYyry7CFZay3W7Xwnaqa1rGrW5Cw13Kw1DX34rWF1xWan2vF13WFy7Gr1UJF40\n qrn2qFn5Za4rZacCm3ZEXasCq-sJn29KB7ZKAUJUUUUr529EdanIXcx71UUUUU7KY7ZEXa\n sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU\n 0xBIdaVrnRJUUUvKb4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2\n IYs7xG6rWj6s0DM7CIcVAFz4kK6r106r15M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v\n e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7CjxVAFwI\n 0_Jr0_Gr1l84ACjcxK6I8E87Iv67AKxVWUJVW8JwA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_\n Jr0_Gr1ln4kS14v26r1Y6r17M2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2\n x26I8E6xACxx1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y6r17\n McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr4\n 1l42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_Jrv_\n JF1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17\n CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0\n I7IYx2IY6xkF7I0E14v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I\n 8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxhVjvjDU\n 0xZFpf9x07je0PfUUUUU=","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":"Changes since [v8]:\n * Add a new test case.\n * Minor formatting fixes.\n * Mark _dl_map_segment_align with attribute_hidden.\n\nChanges since [v7]:\n * Rename tunable glibc.elf.hugetlb to glibc.elf.thp.\n * Rebase on current master.\n\nChanges since [v6]:\n * Move MAX_THP_PAGESIZE to hugepages.\n * Skip THP mode probing when DL_MAP_DEFAULT_THP_PAGESIZE is non-zero.\n\nChanges since [v5]:\n * No functional changes.\n * Add benchmark results to the commit message.\n\nChanges since [v4]:\n * Merge malloc-hugepages into hugepages.\n * Limit the glibc.elf.hugetlb tunable maximum value to 1.\n\nChanges since [v3]:\n * Rebased on current master.\n * Resolved conflicts with recently merged changes.\n * No functional changes intended.\n\nChanges since [v2]:\n * Refactor THP detection into a new generic hugepages abstraction,\n moving helpers out of malloc-hugepages.\n * Add a new tunable, `glibc.elf.hugetlb`, to control THP-aware ELF\n segment alignment.\n * Move the Linux implementation of `_dl_map_segment_align` to\n sysdeps/unix/sysv/linux/, making it generic for Linux (including\n 32-bit) and avoiding wordsize-64-specific overrides.\n * Use `static inline` instead of `static __always_inline`.\n\nChanges since [v1]:\n * Fix CI build failure (-Wunused-function).\n\nThis patch series introduces a small extension point in the ELF loader to allow\narchitecture-specific adjustment of load segment alignment, and uses it to\nimprove Transparent Huge Page (THP) usage on Linux.\n\nPatch 1 removes a redundant declaration of `_dl_map_segments` from\ndl-load.h, avoiding `-Wunused-function` build failures and keeping the\nprototype colocated with its definition.\n\nPatch 2 adds a new helper, `_dl_map_segment_align`, which is called when\ndetermining the maximum alignment for ELF load segments. The generic\nimplementation is a no-op and preserves existing behavior.\n\nPatch 3 introduces a new tunable, `glibc.elf.hugetlb`, which controls\nTHP-aware alignment of ELF loadable segments. By default, the value is 0\nand existing behavior is preserved.\n\nPatch 4 provides a Linux implementation of `_dl_map_segment_align` that\nopportunistically aligns large, suitably aligned, non-writable `PT_LOAD`\nsegments to the system’s default THP page size when THP is configured to\nbe used unconditionally and the tunable is enabled.\n\nPatch 5 enables this behavior by default on LoongArch64 Linux and defines\nthe default THP page size (32MB), matching the architecture’s PMD huge page\ngeometry.\n\nPatch 6 adds a new test for THP alignment of large load segments.\n\n[v8]: https://sourceware.org/pipermail/libc-alpha/2026-April/176440.html\n[v7]: https://sourceware.org/pipermail/libc-alpha/2026-March/175776.html\n[v6]: https://sourceware.org/pipermail/libc-alpha/2026-March/175737.html\n[v5]: https://sourceware.org/pipermail/libc-alpha/2026-March/175694.html\n[v4]: https://sourceware.org/pipermail/libc-alpha/2026-March/175644.html\n[v3]: https://sourceware.org/pipermail/libc-alpha/2026-February/175464.html\n[v2]: https://sourceware.org/pipermail/libc-alpha/2026-February/175394.html\n[v1]: https://sourceware.org/pipermail/libc-alpha/2026-February/175359.html\n\nWANG Rui (6):\n elf: Remove redundant _dl_map_segments declaration from dl-load.h\n elf: Introduce _dl_map_segment_align hook for segment alignment tuning\n tunables: Add glibc.elf.thp tunable for THP-aware segment alignment\n elf: Align large load segments to PMD huge page size for THP\n loongarch: Enable THP-aligned load segments by default on 64-bit\n elf: Add test for THP alignment of large load segments\n\n elf/dl-load.c | 4 +\n elf/dl-load.h | 5 +-\n elf/dl-tunables.list | 8 +\n manual/tunables.texi | 24 +++\n sysdeps/generic/dl-map-segment-align.h | 26 +++\n sysdeps/unix/sysv/linux/Makefile | 8 +-\n .../unix/sysv/linux/dl-map-segment-align.c | 55 +++++++\n .../unix/sysv/linux/dl-map-segment-align.h | 27 ++++\n .../unix/sysv/linux/loongarch/cpu-features.c | 6 +\n .../loongarch/lp64/dl-map-segment-align.h | 22 +++\n sysdeps/unix/sysv/linux/tst-thp-align.c | 149 ++++++++++++++++++\n sysdeps/unix/sysv/linux/tst-thp-size-mod.S | 22 +++\n 12 files changed, 352 insertions(+), 4 deletions(-)\n create mode 100644 sysdeps/generic/dl-map-segment-align.h\n create mode 100644 sysdeps/unix/sysv/linux/dl-map-segment-align.c\n create mode 100644 sysdeps/unix/sysv/linux/dl-map-segment-align.h\n create mode 100644 sysdeps/unix/sysv/linux/loongarch/lp64/dl-map-segment-align.h\n create mode 100644 sysdeps/unix/sysv/linux/tst-thp-align.c\n create mode 100644 sysdeps/unix/sysv/linux/tst-thp-size-mod.S"}