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- choice
- prompt "Preemption Model"
- default PREEMPT_NONE
- config PREEMPT_NONE
- bool "No Forced Preemption (Server)"
- help
- This is the traditional Linux preemption model, geared towards
- throughput. It will still provide good latencies most of the
- time, but there are no guarantees and occasional longer delays
- are possible.
- Select this option if you are building a kernel for a server or
- scientific/computation system, or if you want to maximize the
- raw processing power of the kernel, irrespective of scheduling
- latencies.
- config PREEMPT_VOLUNTARY
- bool "Voluntary Kernel Preemption (Desktop)"
- help
- This option reduces the latency of the kernel by adding more
- "explicit preemption points" to the kernel code. These new
- preemption points have been selected to reduce the maximum
- latency of rescheduling, providing faster application reactions,
- at the cost of slightly lower throughput.
- This allows reaction to interactive events by allowing a
- low priority process to voluntarily preempt itself even if it
- is in kernel mode executing a system call. This allows
- applications to run more 'smoothly' even when the system is
- under load.
- Select this if you are building a kernel for a desktop system.
- config PREEMPT
- bool "Preemptible Kernel (Low-Latency Desktop)"
- help
- This option reduces the latency of the kernel by making
- all kernel code (that is not executing in a critical section)
- preemptible. This allows reaction to interactive events by
- permitting a low priority process to be preempted involuntarily
- even if it is in kernel mode executing a system call and would
- otherwise not be about to reach a natural preemption point.
- This allows applications to run more 'smoothly' even when the
- system is under load, at the cost of slightly lower throughput
- and a slight runtime overhead to kernel code.
- Select this if you are building a kernel for a desktop or
- embedded system with latency requirements in the milliseconds
- range.
- endchoice
- config PREEMPT_RCU
- bool "Preemptible RCU"
- depends on PREEMPT
- default n
- help
- This option reduces the latency of the kernel by making certain
- RCU sections preemptible. Normally RCU code is non-preemptible, if
- this option is selected then read-only RCU sections become
- preemptible. This helps latency, but may expose bugs due to
- now-naive assumptions about each RCU read-side critical section
- remaining on a given CPU through its execution.
- Say N if you are unsure.
- config RCU_TRACE
- bool "Enable tracing for RCU - currently stats in debugfs"
- depends on PREEMPT_RCU
- select DEBUG_FS
- default y
- help
- This option provides tracing in RCU which presents stats
- in debugfs for debugging RCU implementation.
- Say Y here if you want to enable RCU tracing
- Say N if you are unsure.
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