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Linux 2.2 and 2.4 VM Systems Compared
Derek Glidden writes "I got sick of trying to figure out from other people's reports whether or not the 2.4 kernel VM system was broken or not, so I decided to run my own tests, write them up and post them online. The short conclusion is that the 2.4 VM rocks when compared with 2.2, but there's more to it than just that."
From the article:
These were pretty uninteresting - just sitting there watching the kernel compile. Except that at one point, while running the 2.4.13 kernel, the hard drive started grinding away with the drive light pegged on continuously, the display became extremely sluggish and quickly froze up entirely, and about ten minutes later, the hard drive light went off but the machine remained unresponsive, requiring a hard reboot. I don't think this was related to anything I was doing as I wasn't actually doing a compile run at the time - probably just a random occurance, but worth mentioning.
So the machine essentially BSoD'd, but it's not interesting?
...so why does linux have 1 VM? it seems that 2 of them exist, and the BSD's have more... guys, "gimme a hunk" and "page fault" aren't exactly rocket science anymore, particularly with hardware support... the fact that there is room to make a big deal out of this is the problem, not the VMs.
...is that Linux's warts are fully out in the open for all to see. Microsoft would never admit to such failings openly, even though anyone who has used Windows extensively is painfully aware of them.
And it's been my experience that you don't hear, "Linux never crashes" that much anymore. At least I don't say it anymore, whereas I used to. I would still say that a properly configured Linux box is more stable than any Windows box, but I've had my share of lockups. (on the desktop anyway. You'll notice my server has been up for 140+ days. The last reboot was when the power supply died [it's a patched together P166] which interrupted 243 days uptime)
All the mailing lists are public, and all of Linux's problems are there for anyone to see. This allows people to make truly informed decisions about which version of Linux to use, or whether to even use it at all. (Yes, of course these things are also true of *BSD) The current issues are why I still run 2.2.19 on my servers, since none of them get anywhere near enough load to need the newer VM's. "Stable" is definitely a relative term.
Heh, If I ever said anything like this at work I'd get a "Are you afraid to code" out of my boss...
Systems are getting more complex and demands on them get more complex. People have to plan harder and think harder to keep up. It's time to step up to the plate or go home. Years ago Linux didn't need a VM that worked with 4 way SMP and 2 Gig of ram. Today it does.
Claiming that modularity is (I'm paraphrasing) "too hard" comes off more as a cop-out than a reason. If it's hard, do a better job at it. I don't think anyone is claiming that the VM should only take a weekend to do... They just want it done and done right. The argument FOR modularity put forth above is a solid one. Whatever planning/archeteting/coding/testing and debugging that takes. Just do it[tm].
Contrary to popular belief, coding is not all free blow-jobs and beer. Those things cost MONEY!
Claiming that modularity is (I'm paraphrasing) "too hard" comes off more as a cop-out than a reason
Yes, let's make a fundamental, pervasive, part of the kernel hot pluggable, introduce tons of potential bugs and incompatibilities and create lots of work, all for questionable benefit. Engineering involves a series of tradeoffs and, in this case, most people see the pain as being too great for the potential payoff.
But, if you still want to, go right ahead. That's one of the cool thing about Linux: if nobody else wants to do it, you still can.
Reboot macht Frei.