diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 7 | ||||
| -rw-r--r-- | arch/Kconfig | 9 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 1 | ||||
| -rw-r--r-- | kernel/Kconfig.preempt | 19 |
4 files changed, 36 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a10b545c2070..78ab29400dd3 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3916,6 +3916,13 @@ Format: {"off"} Disable Hardware Transactional Memory + preempt= [KNL] + Select preemption mode if you have CONFIG_PREEMPT_DYNAMIC + none - Limited to cond_resched() calls + voluntary - Limited to cond_resched() and might_sleep() calls + full - Any section that isn't explicitly preempt disabled + can be preempted anytime. + print-fatal-signals= [KNL] debug: print fatal signals diff --git a/arch/Kconfig b/arch/Kconfig index 24862d15f3a3..124507907824 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1090,6 +1090,15 @@ config HAVE_STATIC_CALL_INLINE bool depends on HAVE_STATIC_CALL +config HAVE_PREEMPT_DYNAMIC + bool + depends on HAVE_STATIC_CALL + depends on GENERIC_ENTRY + help + Select this if the architecture support boot time preempt setting + on top of static calls. It is strongly advised to support inline + static call to avoid any overhead. + config ARCH_WANT_LD_ORPHAN_WARN bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 21f851179ff0..d3338a87761f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -224,6 +224,7 @@ config X86 select HAVE_STACK_VALIDATION if X86_64 select HAVE_STATIC_CALL select HAVE_STATIC_CALL_INLINE if HAVE_STACK_VALIDATION + select HAVE_PREEMPT_DYNAMIC select HAVE_RSEQ select HAVE_SYSCALL_TRACEPOINTS select HAVE_UNSTABLE_SCHED_CLOCK 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. |