Glibc Now Enables Tuning Framework By Default
Written by Michael Larabel in GNU on 15 June 2017 at 08:39 AM EDT. 5 Comments
GNU --
Since the end of last year Glibc has offered a tunables framework that could be exposed via the --enable-tunables switch at compile-time while now it's being enabled by default.

Glibc's documentation describes their tunables support as:
Tunables is a feature in the GNU C Library that allows application authors and distribution maintainers to alter the runtime library behaviour to match their workload.

The tunable framework allows modules within glibc to register variables that may be tweaked through an environment variable.

As of the latest Git code, tunables is now enabled by default -- no longer requiring the enable-tunables switch at build-time but is now always on unless explicitly disabled.

Siddhesh Poyarekar's argument for enabling the tunables by default, "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 using this trivial patch."

The change will be found in glibc 2.26.
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