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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. |