Tweaking cron for use on laptops
>>>>> "Martin" == Martin Gallant <email@example.com> writes:
Martin> I have been running Debian on my laptop for a few months
Martin> now. Good job guys. Unless I intentionally remove the
Martin> cron package form this machine, the hard drive will not
Martin> spin down. What would be nice is if I could configure
Martin> cron to only run say once per hour. That way I could take
Martin> advantage of the log cycling features of the system.
Martin> Reading through the vixie cron documentation and source,
Martin> there does not appear to be a straightforward way to do
Martin> this. Anyone thought about this?
I've thought about that too. A friend of mine has a Thinkpad that
can do a context dump to a disk partition, and start up right where
you leave off. He told me that there's a desktop system available
that can go to sleep like that also. I want one! I'd like to leave
my machine on all the time.
I've set my drives to spin down, using 'hdparm', but 'update' keeps
them from stopping. There's a patch out, called 'atime' patch, if I
recall, that is supposed to help alleviate this. It says it comes
with a script that puts /dev/* in a ramdisk. I haven't explored it
But what about 'cron'? It ought to set an alarm that would wake up
the computer just before a job is scheduled, run the job, and then go
back to sleep. I suppose that a re-implementation of 'cron' and
'atrun' would be required to make this happen. Q: Does the real time
clock have what would be required? (or a start on that?) How
difficult would that be? Do those computer support something like
this? They must, it seems such an obvious thing.
Another thing I thought of is to install that screensaver hooks
patch, and have the screensaver send a signal to a modified 'update'
daemon. It could SIGUSER1 it, which would cause it to 'sync' and then
toggle to OFF. When the screensaver deactivates, it would SIGUSER1
'update' again, and that would toggle update back on again. (Perhaps
rather than ON/OFF, it would toggle between two update periods given
on the commandline to update. A longer timeout for while
screenblanker is active.)
I tried to hack in a call to sync(); where the screen gets blanked in
the kernel, naively. (Aiieeeeeeeeeeeeeeh!) Can't schedule during an
interrupt. After I finish the big red book, Beginning Linux
Programming, I think I will get that Kernel Internals book and start
on it. :-) There's a lot to learn.
I'm not capable of coding any of that yet; I'm just a beginner. But
I've thought about it some... :-)
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__ _ Karl M. Hegbloom <firstname.lastname@example.org>
/ /(_)_ __ _ ___ __ http://www.inetarena.com/~karlheg
/ / | | '_ \| | | \ \/ / Portland, OR, USA
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