To allocate and free memory is expensive, therefore we should reuse buffers (memory) which have been allocated.

l分配和释放内存是很费时间的，因此我们要反复利用分配好的内存。

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Special system calls, or requests to the UNIX kernel, allocate and free the memory and set permissions; common read and write operations put and get data from the region.

用特殊的系统调用(即对UNIX内核的请求)分配和释放内存并设置权限；通过一般的读写操作读写内存段中的数据。

youdao

Special system calls, or requests to the UNIX kernel, allocate and free the memory and set permissions; common read and write operations put and get data from the region.

用特殊的系统调用(即对UNIX内核的请求)分配和释放内存并设置权限；通过一般的读写操作读写内存段中的数据。

youdao