smp preempt

Referenced from: http://www.cnblogs.com/zhaoyl/archive/2012/09/04/2671156.html Linux process scheduling principleThe target of Linux process scheduling 1. Efficiency: High efficiency means that more tasks are done at the same time. The scheduler will be executed frequently, so the scheduler should be as efficient as possible; 2. Enhance the interactive performance: under the system equivalent load, but also to ensure that the system response time; 3. Ensuring fairness and avoiding hunger and thi

Recently in the kernel frequently used spin lock, spin lock if used improperly, very easy to cause deadlock, in this summary. A spin lock is a mutex device that has only two values: "Lock" and "unlock". It is usually implemented as a bit in an integer value. Want to get a bit related to a particular lock code test. If the lock is available, the lock is set, the code continues to enter the critical section; Conversely, if the lock is obtained by someone else, the code goes into a busy loop (rathe

The target of Linux process scheduling1. Efficiency: High efficiency means that more tasks are done at the same time. The scheduler will be executed frequently, so the scheduler should be as efficient as possible;2. Enhance the interactive performance: under the system equivalent load, but also to ensure that the system response time;3. Ensuring fairness and avoiding hunger and thirst;4.SMP Dispatch: The scheduler must support the multi-processing sys

); } ------- Child_run_nodelay -------- /* Immediately Fork sub-processes, with a very small value for the parent process vruntime */ # Include # Include # Include Int main (INT argc, char * argv []) { Int v = atoi (argv [1]); Nice (v ); If (Fork () = 0) { Printf ("sub/N "); Exit (0 ); } Printf ("Main/N "); } Test process: Nine stub processes are created consecutively. Nice values are dispersed and child_run_delay and child_run_nodelay are run with different nice values. Result: Test resu

Interrupt1. Indicator Range 1.1 Interrupt rateShould be combined with CPU utilization analysis, if CPU utilization is reasonable, a large number of interrupts are acceptable. A large interrupt value, accompanied by a slow performance of the system, indicates a hardware problem1.2 Context Switch RateShould be combined with CPU utilization analysis, if CPU utilization is reasonable, a large number of interrupts are acceptable.When the context switch caused by each call is greater than or equal to

implemented in assembly in entry. S (which, aside from kernel entry code, also contains kernel exit code ). in short, user preemption can occurwhen returning to user-space from a system callwhen returning to user-space from an interrupt handlerKernel preemptionThe Linux kernel, unlike most other UNIX variants and kernel other operating systems, is a fully preemptive kernel. in non-preemptive kernels, kernel code runs until completion. that is, the scheduling is not capable of rescheduling a tas

Example of a kernel-panic [2590.185432] kernel [2590.192874] pgdc0004000 [2590.192881] [00100110] * pgd00000000 [2590.192891] Internalerror: Oops: 17 [#1] PREEMPTSMP [2590. Example of kernel-panic [2590.185432] Unable to handle kernel paging request at virtual address 00100110 [2590.192874] pgd = c0004000 [2590.192881] [00100110] * pgd = 00000000 [2590.192891] Internal error: oops: 17 [#1] preempt smp [2590

is as follows: Void softirq_handler (struct softirq_action *) When the kernel runs a soft interrupt handler, it executes this action function. Its unique parameter is the pointer to the corresponding softirq_action struct. A Soft Interrupt does not preempt another Soft Interrupt. In fact, the only thing that can preempt a Soft Interrupt is the interrupt processing program. However, other soft interrupts-or

/, Lets see: alan@hactar:~/cisco/vpnclient$ ls /etc/opt/cisco-vpnclient/Profiles/sample.pcf Now I will copy the configuration file supplied by my customer to that location so the software can find it: alan@hactar:~/cisco/vpnclient$ sudo cp *.pcf /etc/opt/cisco-vpnclient/Profiles/ Lets check they're there. alan@hactar:~/cisco/vpnclient$ ls /etc/opt/cisco-vpnclient/Profiles/XXX-XXX_XXX-VPN.pcf YYY-YYY_YYY-VPN.pcf ZZZ-ZZZ-ZZZ-1.pcf sample.pcf (Note I 've changed the names of the files to hide so

language to run the foundation, only the machine language and assembly languages when the stack mechanism for the computer is not so important, but with high-level language and functions, the stack has become the basic function of the computer; 3. Interrupt, multi-channel program operating system base point, no interrupt mechanism program can only run from the beginning to the end of the possibility to start running other programs. V. Stack-related registers: ESP (stack-top pointer) EB

Some personal understandings about the spinlock in the kernelBecause the 2.6 kernel can be preemptible, it should be used in the driverPreempt_disable() And preempt_enable () to prevent code segments from being preemptible (IRQ is also implicitly prohibited ). Here, I mainly write down some of my understanding of the spinlock in the kernel, not to tell you anything (because I am not sure about what I said ), instead, I hope that you will be able to tell me the correct things and the wrong things

executing at any time Soft interrupts and Tasklet: The kernel can wake up or dispatch soft interrupts and tasklet at any time, interrupting code that is currently executing Kernel preemption: The Linux kernel is preemptive, so the kernel's task may be preempted by another task Sleep and user space synchronization: Processes that execute in the kernel may sleep and wake up the schedulerScheduler to schedule a new user process execution SMP