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Hello Michael and Bill<BR>
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I waited about 15 - 20 minutes this morning for popcon to finish. My desktop processor is Pentium(R) 4 CPU 2.40GHz with 938 Mb RAM<BR>
That made me read your email again.<BR>
That made me read nice vs ionice, again
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>> <A HREF="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=483465">http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=483465</A>
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As a retired end user of Ubuntu 12.04 Linux I don't have the skills to apply patches to scripts even if I knew which one.
Also the discussion in that posting made me wonder what is best.
So gentlemen, please tell me what consequences I would have if I uninstalled popcon?
Thanks for helping. Kind regards Chas.I
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-- <BR>
<A HREF="mailto:irons.charles@gmail.com">irons.charles@gmail.com</A><BR>
Home +2711 782 8623<BR>
Mobile +2783 588 0028 <BR>
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On Fri, 2014-01-17 at 10:44 +0100, Michael Bunk wrote:
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Hello Bill, hello Charles,
>> Installing anacron instead of cron would not solve your problem. It
>> would just make sure that cronjobs that could not run when your computer
>> is switched off do run later when it is on again.
>>
>> Your problem is related to nice vs ionice, see
>> <A HREF="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=483465">http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=483465</A>
>
> Do you have personal experience with this slowdown ?
> I am willing to reconsider applying the patch in 483465,
> if I am sure it fix a practical problem.
Sorry, no. I was overly optimistic regarding my insight to this
problem. All machines where I have popcon running are virtual machines
powerful enough for popcon to finish in a short time, leaving barely
visible traces in system monitoring (system load shown by munin for
example). Nice and/or ionice are not necessary for them.
Anyways, since Cha(rle)s has a problem, he should really try one patch
from 483465, to see whether it helps. I also think he has anacron
already installed, because it is unlikely his PC is running at 6:47 in
the morning...
I also wonder, why Charles said "The priority is shown as very low",
because cron does not apply any nice/ionice setting and anacron doesn't
anymore since 2.3-17 (29 Mar 2012), see
<A HREF="http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=373950">http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=373950</A>
So if he had an anacron < 2.3-17, some nice setting would be applied by
/etc/anacrontab... and it doesn't help.
But then, from ionice(1):
"Note that before kernel 2.6.26 a process that has not asked for an I/O
priority formally uses "none" as scheduling class, but the I/O
scheduler will treat such processes as if it were in the best-effort
class. The priority within the best-effort class will be dynamically
derived from the CPU nice level of the process: io_priority = (cpu_nice
+ 20) / 5."
That means, Charles' popcon would already be running with ionice "none:
prio 4" (current versions of ionice output "unknown: prio 4", which is
another small bug, <A HREF="https://github.com/karelzak/util-linux/pull/46">https://github.com/karelzak/util-linux/pull/46</A> ).
So my analysis supports Bill's resistance to 483465...
Best regards,
Michael
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