Exploring the Benefits of PAE in the Linux Kernel: Boosting Performance and Efficiency（linux内核pae）

The prevalence of limited RAM size can be seen in many computing devices, such as handheld devices, laptops, and so on. To make better use of the limited RAM and allow them to run more applications, the Physical Address Extension (PAE) was introduced in the Linux kernel. PAE is a feature that allows a processor to access physical memory larger than 4 gigabytes, up to 64 gigabytes. This article will explain what PAE is and the benefits it brings to the Linux Kernel.

PAE enables an operating system to use more memory than is normally allowed by the processor address size. It does this by adding an extra layer of memory mapping, known as multiple page sizes. Each page size is available to every processor on the system, which is why it is known as a “transparent” memory management feature. By using this approach, PAE can access up to 64GB of RAM, which is much larger than the 4GB limit imposed by x86 processors.

The major benefit of using PAE in the Linux kernel is the higher system performance. By adding the extra memory management layer, the kernel can access more physical memory resources, and thus, processes run more efficiently and quickly. This is especially beneficial for multitasking applications, where multiple tasks can be performed simultaneously and simultaneously switch between applications.

Moreover, PAE enables the Linux kernel to use memory more effectively and efficiently. Accessing physical memory resources with PAE means that the system has to access data more quickly than if it were accessing the same data in a single 4GB block. This allows more processes to run concurrently on the system, leading to increased performance and greater efficiency.

PAE in the Linux kernel also offers improved reliability. When errors occur in systems with more than 4GB of RAM, it can become difficult to map memory pages for each process. The additional page sizes provided by PAE make it easier to assign physical memory, leading to fewer process errors and improved system performance.

In summary, PAE in the Linux kernel offers a number of benefits, including improved performance, increased efficiency, and improved reliability. With the extra layer of memory management, systems with up to 64GB of RAM can be accessed and processes can now be run more efficiently, leading to greater performance. Additionally, fewer process errors will occur, leading to improved system reliability.

#ifdef CONFIG_HIGHPTE
pgd_t * pgd_alloc(struct mm_struct * mm)
{
   pgd_t * pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER);
   if (pgd) 
       memset(pgd, 0, THREAD_SIZE);    
   return pgd;
}
#endif