[Beowulf] [OOM killer/scheduler] disabling swap on cluster nodes?

Prentice Bisbal prentice.bisbal at rutgers.edu
Wed Feb 11 08:27:41 PST 2015

On 02/11/2015 12:25 AM, Mark Hahn wrote:
> in other words: buy extra ram to hold your cold pages!  after all, dram
> is only O($10/GB), and disk is O($0.05/GB).  oh, wait...
This comparison is overly simplistic. You're looking only at capacity 
not performance, whereas this conversation is all about about 
performance. If you consider the performance hit of swapping to disk, 
especially in the context of HPC where performance usually overrides 
cost (I said 'usually' - don't flame me!), I think just about everyone 
would agree that $40 for 4 more GB of RAM is a worthwhile investment if 
it has a noticeable effect on improvement.

$40 is only 2% the cost of a $2000 server. If adding that 4 GB of RAM 
increases performance by more than 2%, it's worth the investment. If you 
spend $0.20 on 4 GB of disk but it makes no noticeable improvement on 
performance, you've wasted money, regardless of how cheap it was.

If the same comparison was applied to automobiles, we'd all be driving 
school buses and Ferrari, Lamborghini and Porsche would not exist.


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