Kernel Mode Linux
To measure the degree of performance improvement, I conducted two experiments. Both experiments compared performance of the original Linux kernel and KML. I used the sysenter/sysexit mechanism for performance measurement of the original Linux kernel, instead of the int 0x80 instruction. The experimental environment is shown in Table 1.
In the first experiment, I measured the latency of the getpid and gettimeofday system calls. In the measurement, the system calls were invoked directly by user programs, without libc. The latency was measured with the rdtsc instruction. The result is shown in Table 2.
The result shows that getpid was 36 times faster in KML than in the original Linux kernel, and gettimeofday was twice as fast in KML as it was in the original Linux kernel.
The second experiment is a file I/O benchmark using the Iozone filesystem benchmark. I measured the throughput of four types of file I/O: write, rewrite, read and reread. The measurements were performed on various file sizes from 16KB to 256KB, and the buffer size was fixed at 8KB. The underlying filesystem was ext3. In each measurement, I executed the Iozone benchmark 30 times and chose the best throughput.
The throughput of reread is shown in Table 3. Due to space limitations, the detailed results for write, rewrite and read are omitted.
The result shows that the throughput of reread in KML was improved by 6.8-21%. In addition, write was improved by 0.6-3.2%, rewrite was improved by 3.3-5.3% and read was improved by 3.1-15%.
These experimental results indicate that KML can improve the performance of applications that invoke system calls often, such as those that read or write many small files. For example, web servers and databases can be executed efficiently in KML.
I've performed a benchmark for the Apache HTTP server on KML. It didn't show performance improvement, because I have only a 100-base Ethernet LAN, which became the main bottleneck. If I perform the benchmark on a faster network (say, 1000-base Ethernet or faster), I predict it will show performance improvement.
In the preceeding experiments, it is worth noting that KML eliminated only the overhead of system calls. With some modification to the application, KML will be able to do more for performance improvement. For example, kernel-mode user processes can access I/O buffers directly in the kernel to improve I/O performance.
Toshiyuki Maeda is a PhD candidate in Computer Science at the University of Tokyo. His favorite comics are Hikaru no GO (Hikaru's Go), Jojo no Kimyo na Boken (Jojo's Bizarre Adventure) and Runatikku Zatsugidan (Lunatic Acrobatic Troupe).
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Non-Linux FOSS: Caffeine!
- Tech Tip: Really Simple HTTP Server with Python
- Doing for User Space What We Did for Kernel Space
- Rogue Wave Software's Zend Server
- Parsing an RSS News Feed with a Bash Script
- SuperTuxKart 0.9.2 Released
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