glibc/elf/dl-tunables.list
Adhemerval Zanella 98d5fcb8d0 malloc: Add Huge Page support for mmap
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>
2021-12-15 17:35:38 -03:00

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# Copyright (C) 2016-2021 Free Software Foundation, Inc.
# This file is part of the GNU C Library.
# The GNU C Library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
# The GNU C Library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public
# License along with the GNU C Library; if not, see
# <https://www.gnu.org/licenses/>.
# Allowed attributes for tunables:
#
# type: Defaults to STRING
# minval: Optional minimum acceptable value
# maxval: Optional maximum acceptable value
# env_alias: An alias environment variable
# security_level: Specify security level of the tunable for AT_SECURE binaries.
# Valid values are:
#
# SXID_ERASE: (default) Do not read and do not pass on to
# child processes.
# SXID_IGNORE: Do not read, but retain for non-AT_SECURE
# subprocesses.
# NONE: Read all the time.
glibc {
malloc {
check {
type: INT_32
minval: 0
maxval: 3
env_alias: MALLOC_CHECK_
}
top_pad {
type: SIZE_T
env_alias: MALLOC_TOP_PAD_
security_level: SXID_IGNORE
}
perturb {
type: INT_32
minval: 0
maxval: 0xff
env_alias: MALLOC_PERTURB_
security_level: SXID_IGNORE
}
mmap_threshold {
type: SIZE_T
env_alias: MALLOC_MMAP_THRESHOLD_
security_level: SXID_IGNORE
}
trim_threshold {
type: SIZE_T
env_alias: MALLOC_TRIM_THRESHOLD_
security_level: SXID_IGNORE
}
mmap_max {
type: INT_32
env_alias: MALLOC_MMAP_MAX_
security_level: SXID_IGNORE
minval: 0
}
arena_max {
type: SIZE_T
env_alias: MALLOC_ARENA_MAX
minval: 1
security_level: SXID_IGNORE
}
arena_test {
type: SIZE_T
env_alias: MALLOC_ARENA_TEST
minval: 1
security_level: SXID_IGNORE
}
tcache_max {
type: SIZE_T
}
tcache_count {
type: SIZE_T
}
tcache_unsorted_limit {
type: SIZE_T
}
mxfast {
type: SIZE_T
minval: 0
security_level: SXID_IGNORE
}
hugetlb {
type: SIZE_T
minval: 0
}
}
cpu {
hwcap_mask {
type: UINT_64
env_alias: LD_HWCAP_MASK
default: HWCAP_IMPORTANT
}
}
elision {
enable {
type: INT_32
minval: 0
maxval: 1
}
skip_lock_busy {
type: INT_32
default: 3
minval: 0
}
skip_lock_internal_abort {
type: INT_32
default: 3
minval: 0
}
skip_lock_after_retries {
type: INT_32
default: 3
minval: 0
}
tries {
type: INT_32
default: 3
minval: 0
}
skip_trylock_internal_abort {
type: INT_32
default: 3
minval: 0
}
}
rtld {
nns {
type: SIZE_T
minval: 1
maxval: 16
default: 4
}
optional_static_tls {
type: SIZE_T
minval: 0
default: 512
}
}
mem {
tagging {
type: INT_32
minval: 0
maxval: 255
security_level: SXID_IGNORE
}
}
rtld {
dynamic_sort {
type: INT_32
minval: 1
maxval: 2
default: 2
}
}
}