Kernel Korner - Kernel Mode Linux for AMD64
To see how much performance improvement is possible, I ran the Wisconsin benchmark for MySQL both on the original Linux kernel and on KML, using sql-bench, which comes with MySQL. The experimental environment is shown in Table 1. In the test on KML, both the MySQL server and the benchmark client were executed as kernel-mode user processes, and the patched GNU C Library was used to eliminate the overhead of system call invocations. In addition, the loop count of the test was increased to 10,000, as the default loop count of 10 was too small to produce meaningful results.
Table 1. Experimental Environment
|CPU||Opteron 850 (2.4GHz, L2 cache 1MB) x 4|
|Memory||8GB (Registered DDR1-333 SDRAM)|
|Hard disk||146GB (Ultra320 SCSI 73GB x 2, RAID-0, XFS)|
|OS||Linux kernel 2.6.11 (KML_2.6.11_002)|
|Libc||GNU libc 2.3.5 + patch for KML|
The result is shown in Table 2. The second column shows the total CPU time consumed by the benchmark. The third and forth columns show the breakdown of the total CPU time. The third column shows the CPU time consumed by the user process, and the forth column shows the CPU time consumed by the kernel.
Table 2. Result of Wisconsin Benchmark (in seconds)
The results show that the total CPU time was improved by about 3%. The user CPU time was improved by about 1%, and the system CPU time was improved by about 14%. The result indicates that KML could improve the performance of database applications slightly by eliminating the overhead of system call invocations.
KML is a modified Linux kernel that can execute user processes in kernel mode. By executing in kernel mode, the performance of user programs can be improved by, for example, eliminating the overhead of system call invocations. Besides the performance improvement, KML also can be used to ease inspection and debugging of the kernel and development of kernel modules, because kernel-mode user processes can access the kernel and use large amount of memory and CPU time. I now am considering implementing a helper library to provide kernel-mode user processes with an easy way to access kernel functions and data by exporting them as some kind of shared object.
Resources for this article: /article/8327.
Toshiyuki Maeda is a PhD candidate in Computer Science at the University of Tokyo. His favorite comic artists are Osamu Tezuka, Fujio F. Fujiko and Amin Oka da.
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- July 2016 Issue of Linux Journal
- Tibbo Technology's Tibbo Project System
- Client-Side Performance
- Sony Settles in Linux Battle
- Peppermint 7 Released
- Libarchive Security Flaw Discovered
- Profiles and RC Files
- The Giant Zero, Part 0.x
- Snappy Moves to New Platforms
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide