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With the morecore hook removed, there is not easy way to provide huge pages support on with glibc allocator without resorting to transparent huge pages. And some users and programs do prefer to use the huge pages directly instead of THP for multiple reasons: no splitting, re-merging by the VM, no TLB shootdowns for running processes, fast allocation from the reserve pool, no competition with the rest of the processes unlike THP, no swapping all, etc. This patch extends the 'glibc.malloc.hugetlb' tunable: the value '2' means to use huge pages directly with the system default size, while a positive value means and specific page size that is matched against the supported ones by the system. Currently only memory allocated on sysmalloc() is handled, the arenas still uses the default system page size. To test is a new rule is added tests-malloc-hugetlb2, which run the addes tests with the required GLIBC_TUNABLE setting. On systems without a reserved huge pages pool, is just stress the mmap(MAP_HUGETLB) allocation failure. To improve test coverage it is required to create a pool with some allocated pages. Checked on x86_64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>
45 lines
1.7 KiB
C
45 lines
1.7 KiB
C
/* Malloc huge page support. Generic implementation.
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Copyright (C) 2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, see <https://www.gnu.org/licenses/>. */
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#ifndef _MALLOC_HUGEPAGES_H
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#define _MALLOC_HUGEPAGES_H
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#include <stddef.h>
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/* Return the default transparent huge page size. */
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unsigned long int __malloc_default_thp_pagesize (void) attribute_hidden;
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enum malloc_thp_mode_t
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{
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malloc_thp_mode_always,
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malloc_thp_mode_madvise,
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malloc_thp_mode_never,
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malloc_thp_mode_not_supported
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};
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enum malloc_thp_mode_t __malloc_thp_mode (void) attribute_hidden;
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/* Return the supported huge page size from the REQUESTED sizes on PAGESIZE
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along with the required extra mmap flags on FLAGS, Requesting the value
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of 0 returns the default huge page size, otherwise the value will be
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matched against the sizes supported by the system. */
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void __malloc_hugepage_config (size_t requested, size_t *pagesize, int *flags)
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attribute_hidden;
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#endif /* _MALLOC_HUGEPAGES_H */
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