Comparison
Bin packingvsResource request
Bin packing
the cluster is at ninety percent booked and forty percent used, and adding one more workload still needs a whole new node.
Fitting workloads of assorted sizes onto as few nodes as possible. It is the lever that converts requests into a bill: efficiency is set by how honest requests are and by the ratio of the largest workload to the node size, since one big request can leave an unusable remainder on every node. It is also the reason a cluster can be simultaneously expensive and underused, which reads as a paradox until you look at requests rather than usage.
Full entry →Resource request
you promise the scheduler the workload needs half a core, and that half core is subtracted from the node whether or not you ever use it.
The amount of CPU and memory a workload reserves, used by the scheduler to decide which nodes can hold it. It is a claim on capacity rather than a cap on usage, which is the distinction almost everyone gets wrong first. Requests set far above real usage are how a cluster ends up at thirty percent utilisation and a full bin at the same time, and requests set far below are how a node ends up oversubscribed and thrashing.
Full entry →