[Planetlab-users] Why so high load averages?

[Joe Armstrong]

Hello,

I've just got my first application running on a few PL nodes, and
have observed the following:

  The nodes I am running on are incredibly loaded

 The first node I tried was like this:

 	> uptime
 	03:28:29  up 12 days,  4:02,  0 users,  load average: 13.23, 35.23, 35.21

  load averages of 35 make the machine virtually unusable

	
 The second machine gave:

 	> uptime
 	04:12:21  up 12 days, 14:13,  0 users,  load average: 3.23, 4.70, 4.60

 Which is also pretty bad


  At this point I checked

	http://planetlab.millennium.berkeley.edu/ganglia_v2/
 
  And yes the load averages virtually everywhere are horrific.

  << With  load averages  like this it  is impossible to  do realistic
experiments  -   I  cannot  perform  real   measurements  that  reflect
real-world behaviours, since  in the real world the  machine I interact
with are not heavily this loaded. >>


  Now  http://www.planet-lab.org/php/status.php   lists  10  different
tools that is some sense measure the performance of the system.

  A  nightmare scenario  is where  every research  group in  the world
develops tools to  measure the performance of the  system and they run
all of them at the same time all measuring the same things

  What I had  naively hoped when we joined planetlab  was that I could
write an application  and deploy it on  a lot of nodes and  see how it
ran in  realistic conditions  (this I argued,  was much better  than a
simulation) -

  Now  if   450  experimenters  (I  read  somewhere   there  were  450
experiments) on PL -  *all* do this and they all use  1% of the CPU -
then we'll get 4.5 overload on the  machines - and *none* of us can do
experiments  (all we'll  be  able  to research  is  the properties  of
heavily  loaded  machines  :-)  <<this  is interesting  but  not  that
interesting>>

  This seems to be a show stopper to me, or am I being pessimistic.

  Otherwise, we'd  need a fancy booking  system: You can  have a short
time on  all machines, or a  bigger time on some  sub-set of machines,
and you can trade your slots with other experimenters.

  Will  my first  application have  to be  a booking  system -  or has
anybody got one?

  Comments?

  Cheers

  /Joe