Article:		Why Install Linux on Your Mac?
Subject:		speed
Date:		2004-12-01 05:14:59
From:		wapentake
Linux's primary benefit is speed. If you run some benchmarks on kernel primitives, to compare Linux and Mac OS X, you'll find that Linux is substantially faster in most cases (and faster in probably all cases). When you try Linux, you'll notice that it is snappier. If you don't believe me, try benchmarking yourself. Use the PowerPC cycle counters, and count how long it takes to execute a system call, a thread switch, a floating point fault, a page fault, etc. Mac OS X is so slow. It is easy to see when compiling. A complicated build really stresses a Unix system, and it will show the difference between Linux and OS X. But I'd never run Linux just for its speed. OS X is the nicest OS I've ever used, for many reasons. I can live with its dopey performance. And unfortunately, faster processors won't really help. From the performance perspective, OS X's kernel internals are horrible: they cause massive cache usage. Simple OS X system calls result int cache and TLB misses, when the same system calls on Linux would not. Once you start missing in the processor's caches, your system must use the memory bus. Processor speed doesn't help with memory access. So as long as OS X uses its current construction principles, faster hardware will not scale its performance with processor speed, but rather with memory and memory bus speeds.

Showing messages 1 through 4 of 4.

• speed
  2004-12-02 12:38:07  Paraplegic_Racehorse [Reply | View]
  
  
  I did benchmark it myself. I tried YDL 3.0 on my stock snow iBook when it first came out. While the kernel may or may not work faster, the userland interface - and particularly the GUI (tried KDE, Gnome and Window Maker) - were extremely sluggish compared to Jaguar. In addition, the GUI crashed; a lot. This may have been improved since then, but I will not look back at linux on any of Macs until I retire my current hardware.
  
  That being said, I found NetBSD and Darwin (non-MacOS X) to be significantly snappier than any version of OS X I've used to date. I keep going back to OS X, though. Not for snappy interface or any particular need for a software package or because it Just Works. I keep going back because the interface organization and arrangement is intuitive, elegant and (accounting for its limitations) requires fewer keystrokes or mouse-clicks per task to get any given thing done.
  
  I'm lazy. I bought a computer so it would do some work for me. I want to foist as much of that work off onto the computer as reasonably possible. I do not need eye candy or other customizability; it distracts me from my task. I do need to be able to begin and/or close a task in about half as many user-interactions as Windows, or KDE, or Gnome or whatever wm you'd like to name. That's the true power of OS X, in my opinion.
  
  It allows me to Just Work and stays out of my way.

• speed
  2004-12-02 05:33:14  bitjockey [Reply | View]
  
  
  Will you PLEASE stop talking about benchmarks and processor speed for, like maybe 10 years?!!! That is SO not the point!!
  
  Benchmarks don't help me fulfill my contracts. Supported software that I can trust to do the job does that.
  
  Linux on the Mac is a fad. If you want to work that hard, be my guest. I hope you find ways to overhaul it to make it 90 times faster. But even when you do that, we're gonna need support!

• speed - But Macs Are Slower, Right?
  2004-12-01 12:05:54  williamverna [Reply | View]
  
  
  Quote by Paul Murphy, LinuxInsider
  09/30/04
  
  "The Mac runs Unix on RISC. That makes it inherently more secure and more reliable, as well as more attractive, to people whose jobs or interests require them to go beyond the limits of the GUI.
  
  To many people in the sciences and engineering... the PC versus Mac speed issue boils down to hardware running Unix -- an arena in which UNIX BSD on the G5 has a 50 percent advantage over Linux on the (Intel Processor) Xeon."
  
  Simply put BSD Unix on a PPC is faster and more stable then Linux on x86. Darwin has extremely fast I/O and IP stack, so I have serious reservations believing that a Linux kernel and distrobution ported to a PPC would be faster then the FreeBSD Unix subsystem and Mach kernel used in Darwin.
  
  http://www.linuxinsider.com/story/36964.html
• speed - But Macs Are Slower, Right?
  2004-12-02 01:28:16  wapentake [Reply | View]
  
  
  Be quite clear, I'm not comparing Linux+x86 to Darwin+PowerPC. I compare Linux+PowerPC to Darwin+PowerPC. Linux+PowerPC is thoroughly faster than Darwin+PowerPC.
  
  Your serious reservations are naive. As I said, benchmark it yourself. Or go read the conference proceedings from SOSP in the 90's, and see the papers rip Mach apart, and show why Mach gave microkernels a bad reputation. Microkernels can be fast. Mach is the opposite of fast. Just look at the source code of Mach and BSD in Darwin: they are not designed for speed, but for software management (i.e., to keep things well modularlized). Just one example: in Linux, the parameters for a system call are passed directly via the register file. In Darwin, they are packed up in a memory buffer, passed around, and the results are passed back via another memory buffer, and then everything written back to the register file. That just does wonders for the cache and TLB.
  
  By the way, the I/O and IP stack on Darwin is not fast. It is easy to verify by benchmarking; you can convince yourself rather than believe me. And Darwin doesn't even scale beyond a single processor. When you add Apple's second processor (ever wonder why they don't sell more than two processors?), the performance gap between Linux and Darwin will probably become larger (I haven't measured this myself), but it is easily evident, since Darwin uses several big-kernel-locks, while Linux uses fine grained locking. If the IP stack of Darwin runs on one CPU, it can't for the most part run concurrently on another CPU. Likewise for the I/O system. Fast, huh?
  
  I have an idea for an alternative demonstration of Darwin's diminutive performance. There is currently a project to add Darwin compatibility to BSD and Linux. Go find this project, and try it out. You'll see, without a doubt, that Linux is still faster than Darwin when running Darwin applications, all on PowerPC.