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commit 2ee7711bdd7de9dd30073b223ce29d5cd50320f6
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Author: H.J. Lu <hjl.tools@gmail.com>
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Date:   Sun Dec 13 04:56:41 2020 -0800
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    x86: Remove the default REP MOVSB threshold tunable value [BZ #27061]
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    Since we can't tell if the tunable value is set by user or not:
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    https://sourceware.org/bugzilla/show_bug.cgi?id=27069
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    remove the default REP MOVSB threshold tunable value so that the correct
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    default value will be set correctly by init_cacheinfo ().
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    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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diff --git a/sysdeps/x86/dl-tunables.list b/sysdeps/x86/dl-tunables.list
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index e066313a1d1dd009..89bf296626658900 100644
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--- a/sysdeps/x86/dl-tunables.list
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+++ b/sysdeps/x86/dl-tunables.list
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@@ -39,9 +39,11 @@ glibc {
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       # REP MOVSB.  Since larger register size can move more data with a
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       # single load and store, the threshold is higher with larger register
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       # size.  Note: Since the REP MOVSB threshold must be greater than 8
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-      # times of vector size, the minium value must be updated at run-time.
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+      # times of vector size and the default value is 2048 * (vector size
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+      # / 16), the 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 if
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+      # the tunable value is set by user or not [BZ #27069].
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       minval: 1
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-      default: 2048
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     }
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     x86_rep_stosb_threshold {
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       type: SIZE_T