Another case where SSDs don’t help

The project I’m working on involves compiling a huge number of source files which means we need a sizable amount of scratch space on which to run our experiments.  Our main compute server was running a little short on disk space, so it seemed like the appropriate time to add a new disk. We considered both solid state and traditional spinning platter drives.  The SSD seemed like the better performing options, but we eventually settling on an HDD, as the price of SSDs (due to restriced suppliers) was still prohibitive.

I was curious though how much performance improvement an SSD might have yielded, so I ran a small experiment on my desktop, which does have a (small) SSD.  I built the clang C/C++ compiler version 3.2, first off the HDD (a typical 7200RPM 750GB affair, then off my SSD (a Crucial Sandforce MLC device), and finally off of a ramdisk (Linux tmpfs).

The result?

Less than a 1% difference in compile time between the 3 options.

Similar to the case of Lightroom, it looks like compiling, at least for a mid-sized project (500MB of source) doesn’t benefit from an SSD vs. a hard disk.  Considering that ramdisk and HDD performance were virtuall identical, it seems quite likely that the whole thing never even left the memory of the operating system’s disk cache.

File compression on UNIX

I’ve been moving around a lot of data lately, particularly over the network, so it seemed like a good idea to settle on a compression regimen.  Networks are fast and all, especially at school, but moving multiple gigabytes of data still doesn’t happen instantly.  So I did a comparison of the current mainstream compression programs on Linux.  The system had a fast SSD drive, so operations were mainly CPU bound.

The contenders

  • bzip2 – a fairly popular replacement for gzip, though generally believed to be slower for archiving and unarchiving.
  • compress – interesting for historical purposes and accessing old archives, but no longer really used otherwise.
  • gzip – intended as a free compress replacement, it’s still the most commonly used UNIX compression tool.
  • lzip – an FSF-endorsed LZMA-based encoder claiming higher efficiency than more common tools.
  • lzop – uses a similar algorithm to gzip, but claims to be much faster and so particularly useful for large data files.
  • xz – an LZMA-based encoder claiming high efficiency and speed.
  • zip – still the de-facto standard on Windows, but not particularly popular on Linux.

The Test

To compare, I compressed and decompressed a 220MB tar archive, containing a distribution of the clang C/C++ compiler.  For all program other than compress which only has one setting, I tried the minimum compression setting (-1), the maximum compression setting (-9) and the default setting (no option).

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Wanted: A Small Sleeper Car

In the process of researching cars, I came across the ‘sleeper car‘.  Based on the term ‘sleeper-agent’, the sleeper car is the proverbial wolf in sheep’s clothing – a car that looks like nothing special, yet offers power (and handling) comparable to avowed ‘performance’ models.

It’s an appealing idea.  There are numerous practical reasons for not wanting a car that attracts attention (insurance, cops, even thieves I suppose) but most compelling reason to me is taste.  Most ‘performance’ cars are ugly, showy things that are only too happy to proclaim themselves as hot stuff.  Aggressive styling and appalling colors are all very well if your goal is to get noticed, but it also suggests immaturity and an underlying lack of confidence.

Unfortunately, most automakers seem to be moving in the opposite direction.  Convinced (perhaps correctly) that they can earn extra profits with ‘special edition’ marques, they prefer to take those normal vehicles, redo the styling, add in a stronger engine, and add 20-30% to the sticker price.  While the economics are probably sound, the designs rarely lean in the direction of understated.  So much for slipping under the radar.

I suppose the obvious alternative is to modify one yourself.  Start with a suitably low-key body, and then add the necessary engine and transmission.  The R&B singer Franky Ocean seems to have the right idea, taking an older BMW E30 sedan – and replacing the engine with something a bit more state of the art.  Of course, most of us don’t quite have that sort of budget, so we’ll just have to watch, and envy.

Lessons in Car Shopping

For the past few weeks, I’ve been occupying many of my spare moments shopping for a car.  I admit that reading up about different cars and debating advantages and disadvantages can be fun, but the actually mechanics of poring over craigslist ads is generally less exciting.  In the process, I’ve also learned a bit, both about cars, and about the often bizarre process of buying and selling them.  Here are a few observations on that second point.

CarFax is not all-knowing.  In principle, the CarFax report is the savior of buyers and sellers alike, allowing one to quickly and accurately get a complete picture of any service a car has had done on it.  But while CarFax is often very helpful, it would be a mistake to assume that it is complete.  Some repairs do not make it onto CarFax.  One car I was considering had basically no mention of repairs, yet the mechanic who inspected it noted that it had been almost entirely repainter, and that the bumper had been completely replaced.  So trust, but verify.

A mechanic’s inspection is inexpensive insurance.  Continuing from the previous point, paying a mechanic $100 or $150 to do a full look over the car before buying is simple prudence.  Even if CarFax were omnipotent, it still can’t tell you what sort of repairs will be needed in the near future.  Lots of things wear out, and it’s important to know up front if you will need to budget another $1k for motor mounts and struts, or tires or brakes or whatnot.

‘Driver’s cars’ are a mixed bag.  By ‘driver’s cars’ I mean cars that are generally acknowledged to be fun to drive.  On the upside, they are indeed fun to drive.  And when you drive a lot, that counts.  However, they also tend to attract certain types of owners – often people who like to tweak and modify their cars, not to mention drive them hard.  In theory there’s nothing wrong with such non-stock vehicles, but such mods aren’t always performed correctly, and even when they are, they may have annoying side-effects (e.g. a muffler that’s a lot louder than you really want).

Secondhand pricing takes many things into account.  Early on I was looking for a small, reliable-brand car, and settled on Honda hatchbacks.  I was more than a little surprised to discover that such vehicles were often rarer and more expensive than notably fancier models (BMW coupes) in similar condition.

Private sellers aren’t always.  This is primarily a craigslist thing, but there appear to be a decent number of people who make a living as ‘unofficial’ secondhand car salesmen.  They advertise the cars as theirs, but usually explain that they’re selling the car for a friend or relative when you meet them.  And of course, they always have a reason to meet in a random parking lot, rather than at home.  Aside from the awkwardness of dealing with somebody who isn’t what they say they are, there’s the problem that these people may or may not know the state of the car very well.

Clean cars are clean everywhere.  Engines are dirty places.  All sorts of grime and grit accumulates there, which makes it an obvious place to check to see what the real condition of a secondhand vehicle is.  Some clever souls have thus taken to steam cleaning under the hood.  But even steam cleaning can’t get everything, and on several cars that seemed otherwise sparkling, I brushed my finger in corners under the hood only to have it come out blackened with grease (yes, I probably should have worn gloves).

A False Economy of Cars

My car has been at the shop, awaiting appraisal by insurance, for more than a week.  Today the appraiser finally had a look at it, and deemed the vehicle a ‘total loss’.  In insurance parlance, it means they consider the vehicle more expensive to repair than to replace with an ‘equivalent.’

What horrible tragedy left my car in such a state?  Was I in a head on collision?  Did I smash into a concrete pillar at high speed?  Was my compact sedan the meat in a semi-sandwich?

None of the above.  I hit a pothole.  Not an exceptionally big pothole, considering I couldn’t find it when I drove the same stretch of road a day later in a rental.  Granted, I did hit the pothole at around 65MPH, as I was driving east on I-80, but I’m fairly certain I wasn’t the only one to do so, nor did I do so at higher speed than anyone else.

That unfortunate pothole had the effect of activating two driver’s side airbags in the car. At first I thought the only damage was my eardrum the facade on the door and windshield column that housed the airbags, but as I soon discovered, the airbag’s deployment had also helpfully disconnected the battery cable, preventing the car from starting or running more than a few minutes.

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Revisiting Robert Jordan’s Wheel of Time

Wheel of Time

I began reading Robert Jordan’s Wheel of Time series of novels when I was in junior high school.  They fell under the ‘epic fantasy’ subheading in the local library, but I think ‘exhaustive fantasy’ might have been a more appropriate heading.  At the time, the series had just expanded to 5 books.  At 600+ pages a book, it was by far the longest continuous story I’d ever to read.  And of course it wasn’t yet finished.

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A respite

It is 66 degrees out, overcast, and drizzle has been falling intermittently for the past few hours.  In short, perfect.  Thank you, weather gods, for a long-awaited and much appreciated break from unpleasantness that is an east coast summer.

Long island sound

Looking out from Rye on Long Island Sound

Session B begins

P7023090

Even after 4 years experience with it, I’m still not all that comfortable with the semester system.  Fifteen week blocks just seem too long, with things inevitably starting to drag around week 6 or so.

It also makes the contrast with the summer term even more jarring.  At Columbia, there are two summer sessions, each six weeks long.  As a result, classes that normally met twice a week for 75 minutes now meet twice a week for 190 minutes.  It’s a lot.

Still, it’s nice to have already finished one session and have started the second one on the first week of July.  Hopefully this one goes as smoothly as the last.  So far (today was the first class), so good.

Too clever, by half

My late grandfather was a bright man.  He was the first of his family to go to finish high school, attended City University on scholarship where he received a Bachelor’s degree in Economics and was ABT for the Master’s degree before leaving to go into business for himself.  The IQ test that he took while in the army in WWII classified him as a genius.  Throughout his life, he was a voracious reader who seemed to have been interested in every topic at one point or another, and had done extensive research on all of them.

He often presumed, with good reason, to know more about a given topic than anybody else.  This made him a great person to get advice from, but a poor one to give advice to, for he very rarely listened.  This was particularly true on topics that regarded money.

The downside of all this was that it has taken my uncle and a lawyer the better part of several months to untangle the finances of his estate.  He did everything himself, the result being that he left behind a mess of papers that only he could understand.  And since he did everything himself, none of the stuff is accessible electronically making things like stocks a royal pain to deal with.  The irony of course is that he always believed that his papers were well-organized and set up, and probably for him it was.

I’m not sure there is a particular lesson to be drawn, but after spending much of the day with my uncle and grandmother dealing with banks and lawyers, it’s fairly clear that it is possible to be too smart for one’s own good, and that smart people can just as easily be blind to what they do not understand as everybody else.