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I think this is a bit too simplistic for HPC. Yes, you can go really low cost if all you care is theoretical performance / $. In practice, the cost efficiency o

I think this is a bit too simplistic for HPC. Yes, you can go really low cost if all you care is theoretical performance / $. In practice, the cost efficiency of the system should be seen as 1 / (time to solution for typical applications) / (cost of ownership per year). Even 20% higher memory bandwidth or computational performance per socket matters for the time to solution, since a higher number of nodes is uncertain to replace that due to the communication overhead. As does the performance per watt (costs of cooling). Furthermore, the biggest news for me regarding Ryzen is what they're doing with APUs. Affordable APUs with unified memory supporting HBM (stacked memory) could be a game changer. HBM means an order of magnitude higher memory bandwidth than what we're used to from CPUs, matching what the high end Nvidia Pascal cards are currently offering. By coupling this to a capable multicore X86 CPU with fat cores (as opposed to Knights landing with a higher number of slow cores), could mean tremendous speedups without any programming work for bandwidth bound applications - which includes pretty much any stencil application, e.g. atmospheric models, ocean models, earthquake prediction etc. By 'tremendous' I mean 5-10x per Socket, which is a big deal in these fields.

geezerjay 10y ago
> Yes, you can go really low cost if all you care is theoretical performance / $. Yes that's a fact, and if you're trying to evaluate a solution based on performance/$ then the comparison is made with regards to this factor, and not others. > In practice, the cost efficiency of the system should be seen as 1 / (time to solution for typical applications) / (cost of ownership per year). If you believe that criteria is relevant then you should know that Ryzen's advertised TDP is around 95W while some Opteron 61XX processors have a TDP of 85W. > Furthermore, the biggest news for me regarding Ryzen is what they're doing with APUs. Affordable APUs with unified memory supporting HBM (stacked memory) could be a game changer. For 40$ you can buy 4 opterons with 12 cores each. This means that for less than 1000$ you can put together a 48-core system that supports up to 512 GB of RAM. For around 500$, anyone can put together a 24-core system that also supports a couple of GPUs. Anyone that cares about HPC on a budget knows quite well that used Opterons is where the optimal price/performance ratio can be found, particularly as Opterons already out-perform Xeons in BLAS-based work.
- stolsvik 10y ago
  Would you care to tell how to get hold of such a system, which sites to visit? Thanks!

geezerjay 10y ago

> Yes, you can go really low cost if all you care is theoretical performance / $. Yes that's a fact, and if you're trying to evaluate a solution based on performance/$ then the comparison is made with regards to this factor, and not others. > In practice, the cost efficiency of the system should be seen as 1 / (time to solution for typical applications) / (cost of ownership per year). If you believe that criteria is relevant then you should know that Ryzen's advertised TDP is around 95W while some Opteron 61XX processors have a TDP of 85W. > Furthermore, the biggest news for me regarding Ryzen is what they're doing with APUs. Affordable APUs with unified memory supporting HBM (stacked memory) could be a game changer. For 40$ you can buy 4 opterons with 12 cores each. This means that for less than 1000$ you can put together a 48-core system that supports up to 512 GB of RAM. For around 500$, anyone can put together a 24-core system that also supports a couple of GPUs. Anyone that cares about HPC on a budget knows quite well that used Opterons is where the optimal price/performance ratio can be found, particularly as Opterons already out-perform Xeons in BLAS-based work.

stolsvik 10y ago
Would you care to tell how to get hold of such a system, which sites to visit? Thanks!