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| author | Michal Hocko <mhocko@kernel.org> | 2021-01-18 17:12:19 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2021-02-17 16:12:24 +0300 |
| commit | 6ef869e0647439af0fc28dde162d33320d4e1dd7 (patch) | |
| tree | d9f08abf364f601b9b2ff6225fb4118b9ff739d4 /kernel | |
| parent | 29fd01944b7273bb630c649a2104b7f9e4ef3fa6 (diff) | |
| download | linux-6ef869e0647439af0fc28dde162d33320d4e1dd7.tar.xz | |
preempt: Introduce CONFIG_PREEMPT_DYNAMIC
Preemption mode selection is currently hardcoded on Kconfig choices.
Introduce a dedicated option to tune preemption flavour at boot time,
This will be only available on architectures efficiently supporting
static calls in order not to tempt with the feature against additional
overhead that might be prohibitive or undesirable.
CONFIG_PREEMPT_DYNAMIC is automatically selected by CONFIG_PREEMPT if
the architecture provides the necessary support (CONFIG_STATIC_CALL_INLINE,
CONFIG_GENERIC_ENTRY, and provide with __preempt_schedule_function() /
__preempt_schedule_notrace_function()).
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
[peterz: relax requirement to HAVE_STATIC_CALL]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-5-frederic@kernel.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/Kconfig.preempt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index bf82259cff96..416017301660 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt @@ -40,6 +40,7 @@ config PREEMPT depends on !ARCH_NO_PREEMPT select PREEMPTION select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK + select PREEMPT_DYNAMIC if HAVE_PREEMPT_DYNAMIC help This option reduces the latency of the kernel by making all kernel code (that is not executing in a critical section) @@ -80,3 +81,21 @@ config PREEMPT_COUNT config PREEMPTION bool select PREEMPT_COUNT + +config PREEMPT_DYNAMIC + bool + help + This option allows to define the preemption model on the kernel + command line parameter and thus override the default preemption + model defined during compile time. + + The feature is primarily interesting for Linux distributions which + provide a pre-built kernel binary to reduce the number of kernel + flavors they offer while still offering different usecases. + + The runtime overhead is negligible with HAVE_STATIC_CALL_INLINE enabled + but if runtime patching is not available for the specific architecture + then the potential overhead should be considered. + + Interesting if you want the same pre-built kernel should be used for + both Server and Desktop workloads. |