UM version4.5 benchmarks

Benchmarking UM Version4.5 on different Architectures

Preamble

• Cluster/Parallel file systems are often a bottleneck.
• If the model is not filesystem-bound, it is often (MPI massage) latency-bound.
• Only the master process writes output, this can lead to load-balance issues, which hinder scaling.

Intel SandyBridge

• Test system: Quad socket, 8-core E-4650L (2.60GHz) (L for Low power)
• 20MB L3 cache

MPI message latency
	0 bytes	128 bytes	1024 bytes
between sockets	~0.70us	~1.15us	~2.0us

FAMOUS

Domain Decomposition	Number of Cores	Model-years/day
4x2	8	~327
8x2	16	~450
8x4	32	~480

• The last line of this table shows a real problem scaling beyond 16 cores. Load balance?
• Would like to try to improve file writing performance and re-run.

HadCM3

Domain Decomposition	Number of Cores	Model-years/day
8x2	16	~48
8x4	32	~65