Re: [rfc] "laptop mode"

[Andrew Morton <akpm@zip.com.au>]

Jens Axboe wrote:
> 
> ...
> > Yes, it could be per-queue.  That would add complexity to
> > the already-murky fs/fs-writeback.c.  It that justifiable?
> 
> I dunno, it's up to you. I guess this is mainly IDE specific anyways,
> but you apply the same logic to just one (for instance) of your disks on
> a home desktop system.

Well it's a convenience thing.  Not really worth a lot of code.
I expect most of the proposed functionality could be provided
from userspace anyway via the disk IO number in /proc/stat:

	old_counts=get_counters()
	while 1 {
		sleep 5
		if (old_counts != get_counters()) {
			sync
			sleep 10
			old_counts = get_counters()
		}
	}

This doesn't have the "if we flushed for any reason, reset the
timer" optimisation.  But it will work in 2.4.

So I think I'll just settle for making the ext3 journal timer
expiries tunable.

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