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Tweaking cron for use on laptops

>>>>> "Martin" == Martin Gallant <martyg@computek.net> 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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