71 lines
2.6 KiB
Plaintext
71 lines
2.6 KiB
Plaintext
# x86 specific tunables.
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# Copyright (C) 2017-2022 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
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# License as published by the Free Software Foundation; either
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# version 2.1 of the 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; if not, see
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# <https://www.gnu.org/licenses/>.
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glibc {
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cpu {
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hwcaps {
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type: STRING
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}
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x86_ibt {
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type: STRING
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}
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x86_shstk {
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type: STRING
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}
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x86_non_temporal_threshold {
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type: SIZE_T
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}
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x86_rep_movsb_threshold {
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type: SIZE_T
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# Since there is overhead to set up REP MOVSB operation, REP
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# MOVSB isn't faster on short data. The memcpy micro benchmark
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# in glibc shows that 2KB is the approximate value above which
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# REP MOVSB becomes faster than SSE2 optimization on processors
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# with Enhanced REP MOVSB. Since larger register size can move
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# more data with a single load and store, the threshold is
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# higher with larger register size. Micro benchmarks show AVX
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# REP MOVSB becomes faster apprximately at 8KB. The AVX512
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# threshold is extrapolated to 16KB. For machines with FSRM the
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# threshold is universally set at 2112 bytes. Note: Since the
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# REP MOVSB threshold must be greater than 8 times of vector
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# size and the default value is 4096 * (vector size / 16), the
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# default value and the minimum value must be updated at
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# run-time. NB: Don't set the default value since we can't tell
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# if the tunable value is set by user or not [BZ #27069].
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minval: 1
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}
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x86_rep_stosb_threshold {
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type: SIZE_T
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# Since there is overhead to set up REP STOSB operation, REP STOSB
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# isn't faster on short data. The memset micro benchmark in glibc
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# shows that 2KB is the approximate value above which REP STOSB
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# becomes faster on processors with Enhanced REP STOSB. Since the
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# stored value is fixed, larger register size has minimal impact
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# on threshold.
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minval: 1
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default: 2048
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}
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x86_data_cache_size {
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type: SIZE_T
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}
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x86_shared_cache_size {
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type: SIZE_T
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}
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}
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}
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