Bryan, Here is John's reply.
Bryan Green wrote: [Thu Aug 31 2006, 09:02:40PM EDT] > I'm looking at the kernel config right now. > Is it dangerous to change some of the kernel config options? > Are there specific options that the lustre patches depend on? > For example, since I'll be running this on a box with interactive graphics, > I'd like to > change the Preemption Model to "Preemptible Kernel". In general, my experience is that you're pretty safe. There are exceptions. Obviously you have to have modules enabled etc. You also have to leave enabled the SD_IOSTATS one, which I believe shows up as the legacy /proc/sd filesystem, somewhat non-intuitively. The short answer for that specific one is that CFS claims that you're not supposed to change the preemption model, but I've tried it with various values (some by accident) and never observed a problem. In my travels through the code, I've observed that they *do* have all kinds of locking happening all over the place, and changing that kernel setting *does* cause fairly radical changes in the locking stuff, so I would be willing to believe that lustre does something bad if you change it. But I've never observed a problem. I'd say try it, and if it misbehaves, turn it back :-} -- Joel Martin (kanaka)
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