On Wed, Feb 10, 2021 at 03:18:38PM +0100, Frederic Weisbecker wrote: > Also should we add something like this?
I suppose we can do that, but I'd rather have actual numbers to go with it, I don't think the trampolines are really that terrible. > From: Frederic Weisbecker <frede...@kernel.org> > Date: Wed, 10 Feb 2021 15:11:39 +0100 > Subject: [PATCH] preempt/dynamic: Make PREEMPT_DYNAMIC optional > > In order not to make the small trampoline overhead mandatory for archs > that support HAVE_STATIC_CALL but not HAVE_STATIC_CALL_INLINE, make > PREEMPT_DYNAMIC optional. > > Signed-off-by: Frederic Weisbecker <frede...@kernel.org> > --- > kernel/Kconfig.preempt | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt > index 416017301660..1fe759677907 100644 > --- a/kernel/Kconfig.preempt > +++ b/kernel/Kconfig.preempt > @@ -40,7 +40,6 @@ 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) > @@ -83,11 +82,13 @@ config PREEMPTION > select PREEMPT_COUNT > > config PREEMPT_DYNAMIC > - bool > + bool "Override preemption flavour at boot time" > + depends on HAVE_PREEMPT_DYNAMIC && PREEMPT > + default HAVE_STATIC_CALL_INLINE > 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. > + command line parameter "preempt=" 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 > @@ -99,3 +100,5 @@ config PREEMPT_DYNAMIC > > Interesting if you want the same pre-built kernel should be used for > both Server and Desktop workloads. > + > + Say Y if you have CONFIG_HAVE_STATIC_CALL_INLINE. > -- > 2.25.1 >
