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Enable tunables by default

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All of the major architectures are adopting tunables as a way to add
tuning to the library, from hwcap_mask for aarch64 to HLE for s390 and
ifunc and cache geometry for x86.  Given this adoption and the fact
that we don't want additional tuning knobs to be added outside of
tunables, it makes sense to enable tunables by default using this
trivial patch.

Smoke tested on x86 to ensure that tunables code was built without
specifying it as a configure flag.  I have kept it as --enabled and
not changed it to --disable since we want to still keep the option of
different kinds of front-ends for tunables.

	* configure.ac(--enable-tunables): Enable by default.
	* configure: Regenerate.
	* NEWS: Mention change.
	* manual/install.texi (enable-tunables): Adjust documentation.
	* INSTALL: Regenerate.
This commit is contained in:
Siddhesh Poyarekar 2017-06-15 15:12:54 +05:30
parent 0edbf12301
commit 2c0b90ab44
6 changed files with 27 additions and 19 deletions
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8
ChangeLog
View file

@ -1,3 +1,11 @@
2017-06-15 Siddhesh Poyarekar <siddhesh@sourceware.org>
* configure.ac(--enable-tunables): Enable by default.
* configure: Regenerate.
* NEWS: Mention change.
* manual/install.texi (enable-tunables): Adjust documentation.
* INSTALL: Regenerate.
2017-06-14 Adhemerval Zanella <adhemerval.zanella@linaro.org>
[BZ #18988]

18
INSTALL
View file

@ -177,18 +177,16 @@ will be used, and CFLAGS sets optimization options for the compiler.
'--enable-tunables'
Tunables support allows additional library parameters to be
customized at runtime. This is an experimental feature and affects
startup time and is thus disabled by default. This option can take
the following values:
'no'
This is the default if the option is not passed to configure.
This disables tunables.
customized at runtime. This feature is enabled by default. This
option can take the following values:
'yes'
This is the default if the option is passed to configure.
This enables tunables and selects the default frontend
(currently 'valstring').
This is the default if no option is passed to configure. This
enables tunables and selects the default frontend (currently
'valstring').
'no'
This option disables tunables.
'valstring'
This enables tunables and selects the 'valstring' frontend for

3
NEWS
View file

@ -95,6 +95,9 @@ Version 2.26
as atomic variables to try to implement Dekker's mutual exclusion
algorithm).
* The tunables feature is now enabled by default. This allows users to tweak
behavior of the GNU C Library using the GLIBC_TUNABLES environment variable.
Security related changes:
* The DNS stub resolver limits the advertised UDP buffer size to 1200 bytes,

2
configure vendored
View file

@ -3725,7 +3725,7 @@ fi
if test "${enable_tunables+set}" = set; then :
enableval=$enable_tunables; have_tunables=$enableval
else
have_tunables=no
have_tunables=yes
fi

2
configure.ac
View file

@ -436,7 +436,7 @@ AC_ARG_ENABLE([tunables],
[AS_HELP_STRING([--enable-tunables],
[Enable tunables support. Known values are 'yes', 'no' and 'valstring'])],
[have_tunables=$enableval],
[have_tunables=no])
[have_tunables=yes])
AC_SUBST(have_tunables)
if test "$have_tunables" = yes; then
AC_DEFINE(HAVE_TUNABLES)

13
manual/install.texi
View file

@ -208,18 +208,17 @@ Use this option to disable the vector math library.
@item --enable-tunables
Tunables support allows additional library parameters to be customized at
runtime. This is an experimental feature and affects startup time and is thus
disabled by default. This option can take the following values:
runtime. This feature is enabled by default. This option can take the
following values:
@table @code
@item no
This is the default if the option is not passed to configure. This disables
tunables.
@item yes
This is the default if the option is passed to configure. This enables tunables
This is the default if no option is passed to configure. This enables tunables
and selects the default frontend (currently @samp{valstring}).
@item no
This option disables tunables.
@item valstring
This enables tunables and selects the @samp{valstring} frontend for tunables.
This frontend allows users to specify tunables as a colon-separated list in a