Right now is a great time to buy web hosting, with a lot of companies offering kick-ass Christmas deals. If you have been thinking of hosting a web site, check out the Web Hosting Offers over at Web Hosting Talk.
I’m looking at it myself, specifically The Planet’s deal for a dedicated dual Xeon 2.8 GHz with two 10k RPM 73GB disks, 2 GB RAM, 2500 GB bandwidth, free Red Hat Enterprise for $125 a month. I am sharing it with a friend so it’ll work out to only ~60 bucks a month.
So far I’ve grossly neglected the technical operation of this blog in a Cobbler’s Children sort of way. At the same time, interacting with readers, learning, sharing, and talking has been incredible. I can’t tell you how honored I am that you read my posts. It’s time to take it up a notch. I’ll start with the hosting, for which splitting a dedicated server seems like a great way to go.
I’m also looking for a beefier Unauthenticated Windows box for a client, probably a quad-core, 8-gig box with SQL Server. The Planet has one for $675 a month, including RAID 1, two 250-GB hard drives, and a SQL Server processor license.
If you have any suggestions or questions, say it out loud and it’ll be ok.
For 2,000 years scholars held that heavier objects fall faster than lighter ones, partly because Aristotle couldn’t be bothered to take 2 minutes to experiment. Hell, he even wrote that men have more teeth than women. Isn’t that crazy? And yet, people often rely on this kind of fact-free reasoning to arrive at conclusions about computer performance, among other things. Worse, they spend their IT budgets or sacrifice code clarity based on these flawed ideas. In reality computers are far too complex for anyone to handle performance problems by “reasoning” alone.
Think about a routine in a modern jitted language. Right off the bat you face hidden magic like type coercion, boxing, and unboxing. Even if you know the language intimately, unknowns are introduced as your code is optimized first by the compiler, then again by the JIT compiler. It is then fed to the CPU, where optimizations such as branch prediction, memory prefetching and caching have drastic performance implications. What’s worse, much of the above can and does change between different versions of compilers, runtimes, and processors. Your ability to predict what is going to happen is limited indeed.
To take another example, consider a user thinking of RAID-0 to boost performance. Whether there are any gains depends on a host of variables. What are the patterns of the I/O workload? Is it dominated by seeks and random operations, or is there a lot of streaming going on? Reads or writes? How does the kernel I/O scheduler play into it? How smart are the RAID controller and drivers? How will a journaling file system impact performance given the need for write barriers? What stripe sizes and file system block sizes will be used? There are way too many interdependent factors and interactions for speculative analysis. Even kernel developers are stumped by surprising and counterintuitive performance results.
Measurement is the only way to go. Without it, you’re in the speculation realm of performance tuning, the kingdom of fools and the deluded. But even measurement has its problems. Maybe you’re investigating a given algorithm by running it thousands of times in a row and timing the results. Is that really a valid test? By doing so you are measuring a special case where the caches are always hot. Do the conclusions hold in practice? Most importantly, do you know what percentage of time is spent in that algorithm in the normal use of the application? Is it even worth optimizing?
Or say you’ve got a fancy new RAID-0 set up. You run some benchmark that writes large globs of data to the disk and see that your sustained write throughput is twice that of a single disk. Sounds great, too bad it has no bearing on most real-world workloads. The problem with the naive timing test and the benchmark is that they are synthetic measurements. They are scarcely better than speculation.
To tackle performance you must make accurate measurements of real-world workloads and obtain quantitative data. Thus we as developers must be proficient using performance measurement tools. For code this usually means profiling so you know exactly where time is being spent as your app runs. When dealing with complex applications, you may need to build instrumentation to collect enough data. Tools like Cachegrind can help paint a fuller picture of reality.
For website load times and networks you might use tools like WireShark and Fiddler, as Google did for GMail. In databases, use SQL profiling to figure out how much CPU, reading, and writing each query is consuming; these are more telling than the time a query takes to run since the query might be blocked or starved for resources, in which case elapsed time doesn’t mean much. Locks and who is blocking who are also crucial in a database. When looking at a whole system, use your OS tools to record things such as CPU usage, disk queue length, I/Os per second, I/O completion times, swapping activity, and memory usage.
In sum, do what it takes to obtain good data and rely on it. I’m big on empiricism overall, but in performance it is everything. Don’t trust hearsay, don’t assume that what held in version 1 is still true for version 2, question common wisdom
and blog posts like this one. We all make comical mistakes, even Aristotle did. Naturally, it takes theory and analysis to decide what to measure, how to interpret it, and how to make progress. You need real-world measurement plus reasoning. Like science.
Update August, 2013: Stick Shift is a product that implements this on Windows.
This post teaches you how to set up your computer so that you can generate any keystroke or key combination without taking your hands off home row (the ‘asdf’ row of keys). You can then use the arrow keys, page up/down, shortcuts, and more while in regular typing position. It works across applications, allowing you to type and move about much faster. I call it ‘home row computing’ and it’s something I started doing after I learned touch typing.
I’ll explain the idea and give step-by-step instructions for Windows systems. The first step is to do what power users have done all along: reclaim the Caps Lock key. It is a fine piece of keyboard real estate gone completely to waste, like a landfill in the middle of Manhattan. We must also do some key remapping:
The idea is to change Caps Lock so that it can be combined with other accessible keys to produce all of the faraway keys shown above, plus frequent key combinations and anything else you might want. When I say “map to home row” I mean mapping to keys that can be reached while your hands remain on home row. Nearby letter keys are fine too. For example, Caps Lock+j could become the Up arrow and Caps Lock+e could become Alt+F4.
It is common to turn Caps Lock into Control, but we don’t actually want that because nearly all Control+X combinations are already taken by various programs, so we wouldn’t be able to do much remapping. Some Control+X combinations are very high yield (e.g., the copy/paste/cut combos) so we’ll remap those onto home row. I think the best substitute for Caps Lock is the “Apps Key”. Since no software uses it as a shortcut ingredient, we can hijack it without fear. Also, its normal role is to open a right-click context menu, so that’s a useful thing to have on home row as it helps you stay clear of the mouse.
So download SharpKeys, run it, and turn Caps Lock into the Application Key as shown below:
OK, then click “Write to registry”, log off and back on, and you’re in business. The second step is to download the outstanding AutoHotKey to run our remapping script. AutoHotKey is a must have for Windows power users, featured repeatedly on lifehacker. Since it is a full-on automation and scripting engine there are many ways to do things. However its native key remapping syntax (OldKey::RemappedKey) doesn’t work for us here since we want to map key combinations into single keys. But you don’t have to worry about that, you can just download my ready-made script for either the qwerty (normal) keyboard layout or the Dvorak (freak) layout. Put it anywhere in your file system, then create a shortcut to the script in the Programs > Startup folder so it runs when you log on to Windows. By inspecting the script you’ll be able to tweak it for your tastes. Here’s what it does out of the box:
Thanks to AutoHotKey’s eliteness the layout works well in practice. The timing is not quirky at all and there are zero misfires. If you hold down Caps Lock, you can press the other keys repeatedly and they’ll be remapped. Let go of Caps Lock and they’re back to normal. The script also handles modifiers such as Alt and Shift being pressed along with the key combinations. It’s pretty transparent. If you want to actually toggle caps lock, then Windows Key + Caps Lock will do the trick.
It is a joy to have navigation keys on the home row. It makes browsing, programming and writing much smoother. You can fly through dialogs. Having Esc nearby is not bad either. All in all, I can’t imagine going back to a regular keyboard. Given AutoHotKey’s power you can write scripts to handle key combinations so there are many possibilities. I adapted to this thing pretty fast; the symmetries between page up/up arrow, home/left and so on helped a bit. Again, it’s trivial to pick your own bindings, take a look at other ideas for cursor movement and cook up your own scheme if you wish.
Some quick thoughts regarding text editors. When I first did this I was an Emacs user so having a convenient Control key was crucial, but I still think it’s better to turn Caps Lock into the Apps Key instead. Then you can pick and choose your macro bindings between Control and Caps Lock, and given AutoHotKey’s power you have a lot of leeway. I have since switched to Vim (apostasy!!) and never looked back. Vim users will recognize the beauty of having arrow keys on the home row, but will probably barf at the exact key choices I used since jklh is burned into their brains. Just edit the script. You’ll like navigating without switching modes, and Esc on the home row is great for when you do switch. In Visual Studio this works seamlessly without interfering with any of the native shortcuts.
I’ve tried this out on Windows XP, Server 2003, Vista, and Server 2008, both 32- and 64-bit flavors. No problems that I know of, but use it at your own risk. The script works over Putty so the keys are available on the command line and Vim for all of the Unix boxes I use. If you know of similar approaches in other OSes I’d love to hear it in the comments. Hope this is useful!
Update: Amjith pointed me to XKeymacs, a tool that implements the same idea but for emacs keybindings (you could do a similar thing via AutoHotKey, but this is convenient for sure). Also, you guys in the comments are all in favor of Vim-style HJKL bindings, so if anyone makes a script to do that, I’d be happy to host it.
Update 3: Paul has posted a Linux implementation of this in a comment below. Sweet.
Here’s something I’d love to get from Newegg as a Christmas present to all of geekdom: the ability for users to submit a custom-built system as a product, which can then be reviewed, commented on, and bought by others as a single unit. Wouldn’t that be cool? You build your system there, and submit all the parts (sold by Newegg of course) as the package. People can review it normally, just like any other products, and post issues and real-world benchmarks for the systems as comments. Good custom builds would quickly float to the top. Incompatibilities would be washed out immediately.
As a time-constrained geek, I’d be able to log in, look at the top-rated custom builds, and click “Buy” to get the whole thing. No clicking around. Novices would buy knowing the system has been tested out by many others. Any issues would have solutions posted as comments. Newegg would sell more and build even more value into their site.
Do any hardware sites do this? Am I missing something obvious? If not, then, pretty please, Newegg?