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| author | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-08-13 08:36:29 -0300 |
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| committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2021-12-15 17:35:14 -0300 |
| commit | 5f6d8d97c69748180f0031dfa385aff75062c4d5 (patch) | |
| tree | 97837a8eab4175385c32bacb10dc633b9070f266 /NEWS | |
| parent | cb976fba4c51ede7bf8cee5035888527c308dfbc (diff) | |
| download | glibc-5f6d8d97c69748180f0031dfa385aff75062c4d5.tar.gz glibc-5f6d8d97c69748180f0031dfa385aff75062c4d5.tar.xz glibc-5f6d8d97c69748180f0031dfa385aff75062c4d5.zip | |
malloc: Add madvise support for Transparent Huge Pages
Linux Transparent Huge Pages (THP) current supports three different states: 'never', 'madvise', and 'always'. The 'never' is self-explanatory and 'always' will enable THP for all anonymous pages. However, 'madvise' is still the default for some system and for such case THP will be only used if the memory range is explicity advertise by the program through a madvise(MADV_HUGEPAGE) call. To enable it a new tunable is provided, 'glibc.malloc.hugetlb', where setting to a value diffent than 0 enables the madvise call. This patch issues the madvise(MADV_HUGEPAGE) call after a successful mmap() call at sysmalloc() with sizes larger than the default huge page size. The madvise() call is disable is system does not support THP or if it has the mode set to "never" and on Linux only support one page size for THP, even if the architecture supports multiple sizes. To test is a new rule is added tests-malloc-hugetlb1, which run the addes tests with the required GLIBC_TUNABLE setting. Checked on x86_64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/NEWS b/NEWS index 2532565d77..3b94dd209c 100644 --- a/NEWS +++ b/NEWS @@ -92,6 +92,11 @@ Major new features: --enable-static-pie, which no longer has any effect on the build configuration. +* On Linux, a new tunable, glibc.malloc.hugetlb, can be used to + make malloc issue madvise plus MADV_HUGEPAGE on mmap and sbrk calls. + Setting this might improve performance with Transparent Huge Pages madvise + mode depending of the workload. + Deprecated and removed features, and other changes affecting compatibility: * On x86-64, the LD_PREFER_MAP_32BIT_EXEC environment variable support |