Ubuntu 32-bit, 32-bit PAE, and 64-bit kernel Performance Comparison

At the reader's request, Phoronix recently conducted a special performance test on the Linux kernel, comparing the performance of 32-bit, 32-bit physical address extension (PAE), and 64-bit. LinusTorvalds, the father of Linux systems, once said that there is a 25% performance difference between the system kernel that enables and disables CONFIG_HIGHMEM4G (which enables 32-bit systems to support 4 GB physical memory. Here we will verify it. Lenovo ThinkPadT61 notebook is used in this test.

At the reader's request, Phoronix recently conducted a special performance test on the Linux kernel, comparing the performance of 32-bit, 32-bit physical address extension (PAE), and 64-bit.

Linus Torvalds, the father of Linux systems, once said that there is a 25% performance difference between the system kernel that enables and disables CONFIG_HIGHMEM4G (which enables 32-bit systems to support 4 GB physical memory. Here we will verify it.

Lenovo ThinkPad T61 notebook andUbuntu 9.10System, hardware configuration includes Core 2 Duo T9300 processor,4 GB memoryHitachi 100 GB HTS7220 SATA hard drive, NVIDIA Quadro NVS 140M graphics card, default system and software configuration, including Linux 2.6.31 Kernel, GNOME 2.28.1 desktop environment, X Server 1.6.4, NVIDIA 195.22 graphics card driver, GCC 4.4.1 compiler, and EXT4 file system.

CONFIG_HIGHMEM4G is enabled for the 32-bit Ubuntu kernel by default, but the PAE mode is disabled. In this way, when the system configures 4 GB memory, 1 GB is reserved for the kernel virtual space. The actual available space is only 3 GB, the Ubuntu PAE kernel uses CONFIG_HIGHMEM64G, which can process a maximum of 64 GB memory.Of course, the 64-bit kernel does not have such memory addressing space limitations, which is also the trend of the future.

During the test, the Ubuntu 32-bit PAE mode has enabled swap, CONFIG_HIGHMEM64G instead of CONFIG_HIGHMEM4G, CONFIG_X86_PAE, swap, swap, and disable CONFIG_ASYNC_TX_DMA. The other 32-bit non-PAE mode is consistent.