Messages in this thread | | | Subject | APM support for avoiding waking up laptops every few seconds? | From | Greg Stark <> | Date | 03 Aug 1997 03:52:02 -0400 |
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It would be nice if the laptop feature to spin down the drive weren't nearly completely defeated by Unix's intelligent memory management. I know people have suggested (and implemented) disabling updating atime as a solution, but i think that would only help a little. Really, all disk activity should be avoided and delayed whenever the disk is spun down.
Ideally what i would like to see would be,
1 Just before the APM spins down the disk, a sync should be done. Though i'm not actually sure there's any way to request such notice.
2 Whenever the disk is spun down sys_bdflush should be a noop The idea being that eventually a read will wake up the disk and all those dirty buffers will be flushed within five seconds. This will suck up a lot buffers but if the free list is empty refill_freelist will still work fine.
3 A lot better behaviour in keeping unused buffers around Currently if i run the same program repeatedly i still occasionally hear pages getting read. And if i run a program every 30s it has to be paged in every time.
I realize the buffer architecture has changed in 2.1 hopefully it has improved on the last point.
Incidentally if you're worried about buffers not being committed soon enough and users losing critical data, frankly, hearing the disk spin down is a pretty unambiguous interface indicating that if the machine panicked right that moment any writes would be lost. Users can always run `sync' if it's absolutely critical.
greg
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