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| author | William Hunt <william.hunt@arm.com> | 2025-07-29 15:04:58 +0000 |
|---|---|---|
| committer | Wilco Dijkstra <wilco.dijkstra@arm.com> | 2025-07-29 15:05:51 +0000 |
| commit | 9097cbf5d834990d54dc50585e986dfb7ee34093 (patch) | |
| tree | fd16732baa436514d9d113b1af4400feff1a8910 | |
| parent | 089b4fb90fac8ed53039bc4c465c4d333c6b4048 (diff) | |
| download | glibc-9097cbf5d834990d54dc50585e986dfb7ee34093.zip glibc-9097cbf5d834990d54dc50585e986dfb7ee34093.tar.gz glibc-9097cbf5d834990d54dc50585e986dfb7ee34093.tar.bz2 | |
malloc: Enable THP always support on hugetlb tunable
Enable support for THP always when glibc.malloc.hugetlb=1, as the tunable
currently only gives explicit support in malloc for the THP madvise mode
by aligning to a huge page size. Add a thp_mode parameter to mp_ and check
in madvise_thp whether the system is using madvise mode, otherwise the
`__madvise` call is useless. Set the thp_mode to be unsupported by default,
but if the hugetlb tunable is set this updates thp_mode. Performance of
xalancbmk improves by 4.9% on Neoverse V2 when THP always mode is set on the
system and glibc.malloc.hugetlb=1.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
| -rw-r--r-- | malloc/malloc.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index cf5c02f..ee4ea71 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1871,6 +1871,7 @@ struct malloc_par INTERNAL_SIZE_T arena_max; /* Transparent Large Page support. */ + enum malloc_thp_mode_t thp_mode; INTERNAL_SIZE_T thp_pagesize; /* A value different than 0 means to align mmap allocation to hp_pagesize add hp_flags on flags. */ @@ -1927,7 +1928,8 @@ static struct malloc_par mp_ = .mmap_threshold = DEFAULT_MMAP_THRESHOLD, .trim_threshold = DEFAULT_TRIM_THRESHOLD, #define NARENAS_FROM_NCORES(n) ((n) * (sizeof (long) == 4 ? 2 : 8)) - .arena_test = NARENAS_FROM_NCORES (1) + .arena_test = NARENAS_FROM_NCORES (1), + .thp_mode = malloc_thp_mode_not_supported #if USE_TCACHE , .tcache_count = TCACHE_FILL_COUNT, @@ -2011,6 +2013,11 @@ static inline void madvise_thp (void *p, INTERNAL_SIZE_T size) { #ifdef MADV_HUGEPAGE + /* Only use __madvise if the system is using 'madvise' mode. + Otherwise the call is wasteful. */ + if (mp_.thp_mode != malloc_thp_mode_madvise) + return; + /* Do not consider areas smaller than a huge page or if the tunable is not active. */ if (mp_.thp_pagesize == 0 || size < mp_.thp_pagesize) @@ -5648,12 +5655,9 @@ do_set_hugetlb (size_t value) { if (value == 1) { - enum malloc_thp_mode_t thp_mode = __malloc_thp_mode (); - /* - Only enable THP madvise usage if system does support it and - has 'madvise' mode. Otherwise the madvise() call is wasteful. - */ - if (thp_mode == malloc_thp_mode_madvise) + mp_.thp_mode = __malloc_thp_mode (); + if (mp_.thp_mode == malloc_thp_mode_madvise + || mp_.thp_mode == malloc_thp_mode_always) mp_.thp_pagesize = __malloc_default_thp_pagesize (); } else if (value >= 2) |