This task is known as a context switch.
这任务叫做上下文切换。
上下文开关。
The send system call returns, creating the fourth context switch.
send系统调用返回，结果导致了第四次的上下文切换。
There is an important context switch that deserves a little more attention.
有一个重要的环境转变值得注意。
The send socket call causes a context switch from user mode to kernel mode.
send套接字调用引发了从用户模式到内核模式的上下文切换。
Step four: the write system call returns, creating our fourth context switch.
步骤四：系统调用返回，导致了第4次上下文切换。
The return from the call caused a context switch from kernel back to user mode.
该调用的返回引发了内核模式到用户模式的上下文切换(又一次上下文切换)。
The read call causes a context switch (see Figure 2) from user mode to kernel mode.
read调用(参见图2)引发了一次从用户模式到内核模式的上下文切换。
The return from the call causes another context switch from kernel back to user mode.
该调用的返回引发了内核模式到用户模式的上下文切换(又一次上下文切换)。
Step one: the read system call causes a context switch from user mode to kernel mode.
read() 调用（参见 图 2）引发了一次从用户模式到内核模式的上下文切换。
Step three: the write system call causes a context switch from user mode to kernel mode.
send() 套接字调用引发了从用户模式到内核模式的上下文切换。
Conceptually, a thread context switch can be viewed as a process changing its state.
从概念上讲，一次线程上下文切换相当于进程改变它的状态。
Thread Stack, each thread has a dedicated stack for its own execution and context switch.
线程堆栈，每个线程都有自己执行与上下文切换的专用堆栈。
Internally, a context switch is performed between these two kernels, but this can be done quite fast.
两个内核之间在内部执行上下文切换，但这可以非常快速地完成。
This requires a context switch to the kernel thread to handle the task of moving data to and from disk.
这要求上下文切换到内核线程，以处理将数据移动到磁盘以及从磁盘移出数据的任务。
If not, all resources are used in the virtual processor, saving all of them from a virtual processor context switch.
如果不这样做的话，就需要在虚拟处理器上下文切换的过程中保存该虚拟处理器中使用的所有资源。
A context switch involves saving the context of the running ask and restoring the previously-saved context of the other.
上下文切换包括保存正在运行的任务的上下文和恢复早先保存的另一个任务的上下文。
This causes what is known as a context switch from "user space" to "kernel space," although that's just for you information.
这就引起所谓的从“用户空间”到“内核空间”的上下文切换，不过这仅供了解之用。
A context switch involves saving the context of the running task and restoring the previously-saved context of the other.
上下文切换包括保存正在运行的任务的上下文和恢复早先保存的另一个任务的上下文。
The advantages to this is that if a thread is about to give up a mutex, you don't have to context switch to another thread.
这样做的优点是当一个线程要放弃一个互斥锁的时候，你不需要上下文切换到另外的线程中去。
Operating systems can generally switch (context switching) faster between threads of the same process than between different process.
操作系统通常可以在相同进程中的不同线程之间更快速地切换(上下文切换)，而不是在不同进程之间切换。
However, it is not possible to optimize a hardware context switch, while there might be room for improving the current switching code.
然而，不可能优化硬件上下文切换，而改进当前的软件切换代码还有空间。
To minimize the cost of a virtual processor context switch, the operating system indicates to the hypervisor whether some resources are in use.
为了实现虚拟处理器上下文切换成本的最小化，操作系统将告诉Hypervisor是否正在使用某些资源。
The hardware context switch mechanism was adopted by MPC8250. It makes interrupt responding time of MPC8250 has less relativity with operation system.
MPC8250采取了基于硬件的中断现场保护机制，系统中断响应时间与所采用操作系统相关性较小。
In most practical application, context switch doesn't happen at some time tick, so sometime the execution of timer ISR is useless and wastes CPU time.
在实际应用中，并不是每个时钟节拍都有任务调度，所以有很多时钟中断服务程序的工作是多余的，浪费了CPU资源。
With modern Linux, though, a context switch between distinct processes might take only 15% more time than the corresponding context switch between same-process threads.
然而，在现代的Linux中，不同进程之间的上下文切换所花的时间只比同一进程的线程之间相应的上下文切换多15%。
Some amount of work is done to determine what event occurred and, after a small amount of work, the required task is dispatched to deal with the event (a context switch).
执行一些工作以确定发生了什么事件，然后执行少量工作分配必需的任务以处理此事件(上下文切换)。
Step two: data is copied from the kernel buffer into the user buffer, and the read system call returns. The return from the call caused a context switch from kernel back to user mode.
步骤二：数据从内核空间缓冲区复制到用户空间缓冲区，之后系统调用read返回，这导致了从内核空间向用户空间的上下文切换。
When a context switch occurs in cases such as virtual processor conferring its cycles to another virtual processor, it will be required to save the entire program visible processor state.
在出现上下文切换的情况下(如虚拟处理器将其周期交换给另一个虚拟处理器的时候)，必须保存整个程序的可见处理器状态。
Each processor on the CPU has its own CSA (current save area) pointer that points to the MST that is to be used when a thread or interrupt handler is interrupted or swapped due to context switch.
CPU上的每个处理器都拥有自己的CSA(当前保存区)指针，指向当线程或中断处理程序由于上下文切换而被中断或交换时使用的MST。
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