Operating System Examples

Windows Threads

• Windows API – primary API for Windows applications

• Implements the one-to-one mapping, kernel-level

• Each thread contains
  • A thread id
  • Register set representing state of processor
  • Separate user and kernel stacks for when thread runs in user mode or kernel mode
  • Private data storage area used by run-time libraries and dynamic link libraries (DLLs)

• The register set, stacks, and private storage area are known as the context of the
  thread

• The primary data structures of a thread include:
  • ETHREAD (executive thread block) – includes pointer to process to which thread
    belongs and to KTHREAD, in kernel space
  • KTHREAD (kernel thread block) – scheduling and synchronization info, kernel-mode
    stack, pointer to TEB, in kernel space
  • TEB (thread environment block) – thread id, user-mode stack, thread-local storage,
    in user space

Linux

• Linux refers to them as tasks rather than threads

• Thread creation is done through clone() system call

• clone() allows a child task to share the address space of the parent task (process)
  • Flags control behavior

• struct task_struct points to process data structures (shared or unique)