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Most applications will run on either Broadwell or Skylake nodes, and performance differences are expected to be small compared to job waiting times. Therefore we recommend that you do not select a specific node type for your jobs. If it is necessary, use <code>--constraint=skylake</code> or <code>--constraint=broadwell</code>. See [[Running_jobs#Specifying_a_CPU_architecture|Specifying a CPU architecture]]. | Most applications will run on either Broadwell or Skylake nodes, and performance differences are expected to be small compared to job waiting times. Therefore we recommend that you do not select a specific node type for your jobs. If it is necessary, use <code>--constraint=skylake</code> or <code>--constraint=broadwell</code>. See [[Running_jobs#Specifying_a_CPU_architecture|Specifying a CPU architecture]]. | ||
== Performance | = Submitting and running jobs policy = | ||
Effective since '''April 17, 2019''', the jobs running in the <code>/home</code> filesystem are no longer allowed on cedar. The policy is put in place to reduce the load on that file system and improve the responsiveness for interactive work. If you get the following message: '''you are not permitted to submit jobs from that directory''', when submitting a job, transfer the files from that directory either to your <code>/project</code> or <code>/scratch</code> directories and submit the job from there. | |||
= Performance = | |||
Theoretical peak double precision performance of Cedar is 936 teraflops for CPUs, plus 2,744 for GPUs, yielding over 3.6 petaflops of theoretical peak double precision performance. 22 fully connected "islands" of 32 base or large nodes each have 1024 cores in a fully non-blocking topology (Omni-Path fabric), with each island designed to yield over 30 teraflops of double-precision performance (measured with high performance LINPACK). There is a 2:1 blocking factor between the 1024 core islands. The Skylake nodes also span 20 non-blocking islands of 32 nodes each, forming islands of 1536 cores. | Theoretical peak double precision performance of Cedar is 936 teraflops for CPUs, plus 2,744 for GPUs, yielding over 3.6 petaflops of theoretical peak double precision performance. 22 fully connected "islands" of 32 base or large nodes each have 1024 cores in a fully non-blocking topology (Omni-Path fabric), with each island designed to yield over 30 teraflops of double-precision performance (measured with high performance LINPACK). There is a 2:1 blocking factor between the 1024 core islands. The Skylake nodes also span 20 non-blocking islands of 32 nodes each, forming islands of 1536 cores. | ||
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