The Linux Kernel Analysis And Real-time Transformation

Study of Real-time Operating System (RTOS) is now a hot topic. Compared with common OS, RTOS has the characteristic that its validity does not only depend on the logistic correctness, but also depends on outputting result in time. RTOS are wildly used in fields, such as defense, industrial automation control and communication.After being released in early 2004, Linux 2.6 kernel has been proved to be stable and high efficient. Compared with 2.4 version kernel, 2.6 has been improved in real-time performance by adopting some new technologies, such as preemptive kernel, new O(1) schedule algorithm etc. Although the developer of RTOS can benefit from these changes, Linux 2.6 is still not a real-time kernel. All these changes make it possible to convert Linux to a RTOS. So the reforming of Linux kernel is needed which improve real-time performance.On the basis of reading and research of Linux 2.6 kernel resource codes, the paper gives the deep analyses and summaries of Linux 2.6 kernel's task scheduler mechanism, timer mechanism. As the improvement solution, As to the problem of Linux 2.6 kernel's too large timer granularity in timer mechanism, One-shot Mode is introduced in Linux timers from the principle of timer mechanism improvement in Kurt-Linux.the new timer mechanism is implemented skillfully. The new timer mechanism makes the system reached the microsecond level timer precision and maintains its original Load capability. as to the problem of Linux 2.6 kernel lacking in real-time scheduling algorithms and policies in the scheduler mechanism, the "laxity" notion is introduced from the good dynamic real-time schedule algorithm LSF(laxity small first). Combination of the laxity and the new task scheduler data structure in Linux2.6 enhances the system's real-time scheduler capability as well as maintains the original O (1) scheduling characteristic;From the testing results, we can see that the Linux 2.6 kernel has the stronger real-time capability .It is more fit for the real-time application in embedded fields.