Run prelink and other stuff not in cron but when screensaver is active.

[Jaap A. Haitsma]

I sometime get a bit frustrated that a cron job starts while I'm 
working. Wouldn't it be nicer that this stuff would run when I'm not 
doing any work. I.e. when the screensaver is active. Maybe as a minor 
enhancement when the screensaver is active and there is not a process 
asking for cpu power /disk access. Sometimes I'm running compiling jobs 
which take quite a while.

Jaap

[Roland McGrath]

I think what you want is a new cron feature to use criteria other than just
time to decide when to run something.  i.e., so you can say "every day,
when idle or every week even if not idle".

[Bill Rugolsky Jr.]

On Wed, Oct 29, 2003 at 08:26:55PM +0100, Jaap A. Haitsma wrote:
> I sometime get a bit frustrated that a cron job starts while I'm 
> working. Wouldn't it be nicer that this stuff would run when I'm not 
> doing any work. I.e. when the screensaver is active. Maybe as a minor 
> enhancement when the screensaver is active and there is not a process 
> asking for cpu power /disk access. Sometimes I'm running compiling jobs 
> which take quite a while.

Several things.

1. anacron(8)
2. batch(1)
3. nice(1) and renice(8)
4. xscreensaver-command(1)

With some combination of these, it is not too difficult to roll
a (sub-optimal) solution using nothing more than scripting.

xscreensaver-command(1):

-watch  Prints a line each time the screensaver changes state: when the
         screen  blanks,  locks,  unblanks,  or when the running hack is
         changed.  This option never returns; it is intended for use  by
         shell  scripts  that  want  to react to the screensaver in some
         way.  An example of its output would be:

BLANK Fri Nov  5 01:57:22 1999
              RUN 34
              RUN 79
              RUN 16
              LOCK Fri Nov  5 01:57:22 1999
              RUN 76
              RUN 12
              UNBLANK Fri Nov  5 02:05:59 1999

The above shows the screensaver activating, running three  dif-
         ferent  hacks,  then  locking (perhaps because the lock-timeout
         went off) then unblanking (because the user became active,  and
         typed  the correct password.)  The hack numbers are their index
         in the â list (starting with 1,  not  0,  as  for  the
         -select command.)

For  example, suppose you want to run a program that turns down
         the volume on your machine when the screen blanks, and turns it
         back  up  when the screen un-blanks.  You could do that by run-
         ning a Perl program like the following in the background.   The
         following  program  tracks the output of the -watch command and
         reacts accordingly:

#!/usr/bin/perl

my $blanked = 0;
              open (IN, "xscreensaver-command -watch |");
              while (<IN>) {
                  if (m/^(BLANK|LOCK)/) {
                      if (!$blanked) {
                          system "sound-off";
                          $blanked = 1;
                      }
                  } elsif (m/^UNBLANK/) {
                      system "sound-on";
                      $blanked = 0;
                  }
              }

Note that LOCK might come either with or without  a  preceeding
         BLANK  (depending  on whether the lock-timeout is non-zero), so
         the above program keeps track of both of them.

Regards,

Bill Rugolsky

[Pádraig Brady]

Bill Rugolsky Jr. wrote:
> On Wed, Oct 29, 2003 at 08:26:55PM +0100, Jaap A. Haitsma wrote:
> > I sometime get a bit frustrated that a cron job starts while I'm 
> > working. Wouldn't it be nicer that this stuff would run when I'm not 
> > doing any work. I.e. when the screensaver is active. Maybe as a minor 
> > enhancement when the screensaver is active and there is not a process 
> > asking for cpu power /disk access. Sometimes I'm running compiling jobs 
> > which take quite a while.
>
> Several things.
> anacron(8)
> batch(1)
> nice(1) and renice(8)
> xscreensaver-command(1)
>
> With some combination of these, it is not too difficult to roll
> a (sub-optimal) solution using nothing more than scripting.

true.
This reminds me, that it's seriously annoying
that xscreensaver runs for vnc sessions. Seems
like an easy fix.

Pádraig.

[Tim Waugh]

On Thu, Oct 30, 2003 at 09:58:23AM +0000, [e-mail] wrote:
> This reminds me, that it's seriously annoying
> that xscreensaver runs for vnc sessions. Seems
> like an easy fix.

How do you suggest?  There are several possible approaches.

Tim.
*/

[Alan Cox]

> > This reminds me, that it's seriously annoying
> > that xscreensaver runs for vnc sessions. Seems
> > like an easy fix.
>
> How do you suggest?  There are several possible approaches.

Its actually useful in a thin client environment that it does. And the
user can configure blanking easily enough

[Pádraig Brady]

Alan Cox wrote:
> > > This reminds me, that it's seriously annoying
> > > that xscreensaver runs for vnc sessions. Seems
> > > like an easy fix.
> >
> > How do you suggest?  There are several possible approaches.
>
> Its actually useful in a thin client environment that it does. And the
> user can configure blanking easily enough

True, though I think xcreensaver should be off by default under vnc.

Pádraig.

Run prelink and other stuff not in cron but when screensaver

[Alan Cox]

> > Its actually useful in a thin client environment that it does. And the
> > user can configure blanking easily enough
>
> True, though I think xcreensaver should be off by default under vnc.

Why ?

Run prelink and other stuff not in cron but when screensaver

[Chuck Wolber]

> > True, though I think xcreensaver should be off by default under vnc.
>
> Why ?

Why send all of that traffic over a network? Even if it is local, it just 
seems like a waste to me...

Run prelink and other stuff not in cron but when screensaver

[Pádraig Brady]

Alan Cox wrote:
> > > Its actually useful in a thin client environment that it does. And the
> > > user can configure blanking easily enough
> >
> > True, though I think xcreensaver should be off by default under vnc.

Because to ship screensaver output over vnc takes a lot of CPU
and network resources. IMHO this should not happen by default,
because newly setup machine with a few users running vncserver
hammers the machine.
     If they want to setup screensavers explicitly, fine, but
at least you can lart them for that :-)

Pádraig.

Run prelink and other stuff not in cron but when screensaver

[Alan Cox]

> Because to ship screensaver output over vnc takes a lot of CPU
> and network resources. IMHO this should not happen by default,
> because newly setup machine with a few users running vncserver
> hammers the machine.

Just as true for non Vnc screensavers
>  If they want to setup screensavers explicitly, fine, but
>
> at least you can lart them for that :-)

It sounds to me more of an argument for using 'blank' as the 
default screensaver except on localhost ?

[Jakub Jelinek]

On Thu, Oct 30, 2003 at 09:58:23AM +0000, [e-mail] wrote:
> Bill Rugolsky Jr. wrote:
> > On Wed, Oct 29, 2003 at 08:26:55PM +0100, Jaap A. Haitsma wrote:
> > > I sometime get a bit frustrated that a cron job starts while I'm 
> > > working. Wouldn't it be nicer that this stuff would run when I'm not 
> > > doing any work. I.e. when the screensaver is active. Maybe as a minor 
> > > enhancement when the screensaver is active and there is not a process 
> > > asking for cpu power /disk access. Sometimes I'm running compiling jobs 
> > > which take quite a while.
> >
> > Several things.
> > anacron(8)
> > batch(1)
> > nice(1) and renice(8)

/etc/cron.daily/prelink
starts with renice +19 -p $$ >/dev/null 2>&1

I totally agree with Roland, this should be solved in cron. When a new
category for run daily when the system is most idle or something like
that is added, I'll certainly move prelink to that category.
(and slocate.cron should fall in exactly the same category).

But, even current prelink cron job, if there are no changes
on the system it shouldn't do too many disk accesses nor take much CPU time.

Jakub