51 lines
1.9 KiB
Diff
51 lines
1.9 KiB
Diff
From bc6d79f4ae99206e7ec7d6a8c5abf26cdefc8bff Mon Sep 17 00:00:00 2001
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From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Date: Thu, 23 Nov 2023 14:29:15 -0300
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Subject: [PATCH] malloc: Improve MAP_HUGETLB with glibc.malloc.hugetlb=2
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Even for explicit large page support, allocation might use mmap without
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the hugepage bit set if the requested size is smaller than
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mmap_threshold. For this case where mmap is issued, MAP_HUGETLB is set
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iff the allocation size is larger than the used large page.
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To force such allocations to use large pages, also tune the mmap_threhold
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(if it is not explicit set by a tunable). This forces allocation to
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follow the sbrk path, which will fall back to mmap (which will try large
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pages before galling back to default mmap).
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Checked on x86_64-linux-gnu.
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Reviewed-by: DJ Delorie <dj@redhat.com>
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Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
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Conflict: this adapt the context from the origin commit.
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---
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malloc/arena.c | 12 +++++++++---
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1 file changed, 9 insertions(+), 3 deletions(-)
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diff --git a/malloc/arena.c b/malloc/arena.c
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index f8e425e1..33dbc5ae 100644
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--- a/malloc/arena.c
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+++ b/malloc/arena.c
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@@ -366,9 +366,15 @@ ptmalloc_init (void)
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TUNABLE_GET (mxfast, size_t, TUNABLE_CALLBACK (set_mxfast));
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TUNABLE_GET (hugetlb, size_t, TUNABLE_CALLBACK (set_hugetlb));
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if (mp_.hp_pagesize > 0)
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- /* Force mmap for main arena instead of sbrk, so hugepages are explicitly
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- used. */
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- __always_fail_morecore = true;
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+ {
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+ /* Force mmap for main arena instead of sbrk, so MAP_HUGETLB is always
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+ tried. Also tune the mmap threshold, so allocation smaller than the
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+ large page will also try to use large pages by falling back
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+ to sysmalloc_mmap_fallback on sysmalloc. */
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+ if (!TUNABLE_IS_INITIALIZED (mmap_threshold))
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+ do_set_mmap_threshold (mp_.hp_pagesize);
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+ __always_fail_morecore = true;
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+ }
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#else
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if (__glibc_likely (_environ != NULL))
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{
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--
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2.33.0
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