| |||||||||||||
Better than POSIX?Better than POSIX?Posted Mar 17, 2009 22:30 UTC (Tue) by dhess (guest, #7827)In reply to: Better than POSIX? by xav Parent article: Better than POSIX?
Maybe the answer is a new set of guarantees for Linux's POSIX API, e.g. an overwriting rename() will either leave the old or new version to disk, atomically. Yeah, I've come to a similar conclusion. Perhaps the rename() semantics alone is sufficient. It's simple enough conceptually that it might be relatively easy to get other operating systems to adopt the new semantics, too, at least for the filesystems that can support it. And it sounds like there's already a quite common belief amongst application developers that all filesystems behave this way, anyway. In a previous life, I worked on memory ordering models in CPUs and chipsets. During this recent ext4 hubbub, it dawned on me that the issues with ordering and atomicity in high-performance filesystem design may be isomorphic to memory ordering. Even if that's not strictly true, there's probably a lot to be learned by filesystem designers and API writers from modern CPU memory ordering models, in any case, because memory ordering is a well-explored space by this point in the history of computer engineering; and I don't just mean the technical semantics, either, but the whole social aspect, too, i.e., how to balance good performance with software complexity, how much of that complexity to expose to application programmers, who often have neither the time nor the background to understand all of the tradeoffs, let alone dot all the "i"s and cross all the "t"s, etc. Anyway, changing rename's semantics as you suggest would be the equivalent of a "release store" in memory ordering terms, and seems to be exactly the right kind of tradeoff in this situation.
(Log in to post comments)
Better than POSIX? Posted Mar 17, 2009 23:04 UTC (Tue) by quotemstr (subscriber, #45331) [Link] Thanks for that comment --- it's amazing how much knowledge we're rediscovering in computing. It's almost as if we're coming out of some kind of dark age.One thing that struck me was a comment on a Slashdot story about a "breakthrough" in data center energy optimization. The comment showed that the problem of deciding when to boot up additional servers to meet demand was isomorphic to the problem of steam boiler management --- right down to the start-up and constant energy costs --- and that the problem had already been thoroughly addressed in literature from the turn of the last century.
Better than POSIX? Posted Mar 17, 2009 23:52 UTC (Tue) by dhess (guest, #7827) [Link]
Hmm, that is interesting! I'll file the steam boiler analogy away for later use.
Alan Kay never misses an opportunity to point out that our field has a terrible track record when it comes to learning from, or even being aware of, our history, let alone that of other related fields. There's a lot of unfortunate "rediscovering" of knowledge in computer science and engineering. (I'm as guilty of it as anyone.) I think it's a good habit to consider Alan's admonishment when we're faced with challenges or seeking solutions to problems, so I guess I'll follow his lead by mentioning it here :)
Better than POSIX? Posted Mar 17, 2009 23:57 UTC (Tue) by rahvin (subscriber, #16953) [Link]
That's cause FOSS has opened up the gates to allow technology experience and knowledge to flow around society instead of being trapped behind the corporate copyright, trade secret and patent. What was once a segregated system where you could only learn from those who worked with you directly has turned into a system where the experts from every company provide wisdom and training to the new kids at every company. The corporate policies that once locked behind the corporate veil the experts who built the foundation we are trying to build upon has been blasted apart and is now being shared to everyone's benefit.
Imagine for how many years the wheel was reinvented over and over again at hundreds of companies as people relearned how to code something the proper way for a certain scenario. It's scary to think how fast we could have developed software if it had been FOSS all along instead of corporations each trying to slit each others throats. In the case of computer information systems the sharing of code accelerates the total technology much faster than the private corporate system of the past ever has. Of course this isn't always true. Niche software will probably always need the economic support closed systems provide even if it divides the efforts among a few companies who reinvent each other's innovations.
Better than POSIX? Posted Mar 26, 2009 10:56 UTC (Thu) by massimiliano (subscriber, #3048) [Link] That is one explanation. Another one is that we don't have an "engineering culture" in software development.
I mean, software developers are not necessarily engineers, so they rarely know about issues like steam boiler management.
Now, I'm not claiming engineers are necessarily better than others in this sense. I know many guys who quit college and they are better than me in understanding aspects of different technologies. What I'm claiming is that very often people reinvent the wheel not because the previous wheel was a secret, but because they do not have this "engineering culture" of knowing different kinds of wheels in advance, and being able to understand correctly in which ways they are similar and when they are relevant.
And without going to different disciplines, how many software developers have a good "culture" about the basic concepts needed in their job, like recurrent algorithms and patterns?
My 2c,
Better than POSIX? Posted Mar 27, 2009 1:01 UTC (Fri) by nix (subscriber, #2304) [Link]
HEAR HEAR.
I'd estimate that I spend 20% of my time at work ripping out people's
(And do the reimplementations stop? No! I ditched a chained hash table
I mean it's not as if computers are bad at searching for things, but half
Pride Posted Mar 27, 2009 5:49 UTC (Fri) by quotemstr (subscriber, #45331) [Link]
One explanation behind all these square wheels is the phase every programmer goes through during which he overestimates his abilities, has no sense of scale, and lacks sense for robustness. In short, he's proud, ignorant, and dangerous. He believes that libraries are bloated and slow, that he can out-perform standard implementations. He optimized prematurely, avoids function calls, abuses the ternary operator, and doesn't use a profiler.
Eventually, these programmers grow up, but in the meantime, they've written a significant amount of horrible code. I've seen this pattern again and again. As the parent mentioned, software developers have no "engineering culture." I imagine that in more established engineering disciplines, students have the above attitude beaten out of them before they graduate.
|
|||||||||||||