tag:blogger.com,1999:blog-3155908228127841862.post321909246198220608..comments2023-06-28T10:04:44.463-06:00Comments on The Perils of Parallel: 20 PFLOPS vs. 10s of MLOC: An Oak Ridge ConundrumGreg Pfisterhttp://www.blogger.com/profile/12651996181651540140noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-3155908228127841862.post-50238858012746714812012-01-16T15:01:29.441-07:002012-01-16T15:01:29.441-07:00IMHO AMD's APU or an Atom/ARM chip packaged wi...IMHO AMD's APU or an Atom/ARM chip packaged with a commodity GPU is the way to go. Who really cares about running a petaflop's worth of particles due to the extreme latency between iterations which is at minimum the speed of light distance between compute nodes? 99% of particle simulation computations fit on a single high end GPU. Big data problems are all about caching and striping across multiple machines to lower bottlenecks and have failover if a node dies which will start happening with probability one in the very near future.Chad Brewbakerhttps://www.blogger.com/profile/10443154815748267611noreply@blogger.comtag:blogger.com,1999:blog-3155908228127841862.post-43906835321546472202012-01-16T12:00:10.249-07:002012-01-16T12:00:10.249-07:00No, I hadn't considered that because, frankly,...No, I hadn't considered that because, frankly, I didn't really know. Certainly Roadrunner has a similar set of issues.<br /><br />Thanks for the information!Greg Pfisterhttps://www.blogger.com/profile/12651996181651540140noreply@blogger.comtag:blogger.com,1999:blog-3155908228127841862.post-67137735443797013822012-01-15T20:43:14.622-07:002012-01-15T20:43:14.622-07:00Greg, with regard to the number of codes that can ...Greg, with regard to the number of codes that can be ported to run on a GPU-based Titan system: Have you considered how many codes were ever actually run on Roadrunner at LANL? From everything I've read and heard, it is extremely challenging to program Roadrunner and get good performance out of the Cell processors (Roadrunner is a hybrid system, with AMD hosts and Cell accelerators). I'd be willing to bet that the only codes successfully ported to or written for Roadrunner involved little more than one or two simple but CPU intensive kernels; I didn't hear of any "multiphysics" codes being ported to Roadrunner. From a production computing standpoint, Roadrunner is largely a failure. From a "pushing the limits of technology" standpoint, though, it might be considered a success.<br /><br />That's a pretty bad precedent for a GPU-based Titan, since Titan is intended for production computing. However, there are far more developers with experience programming Nvidia GPUs than there are programming Cell, so perhaps the situation won't be so bad.<br /><br />My bet is that a handful of codes will be able to use the GPUs in Titan effectively, with at least a few of them having a kernel that can be tuned well enough to pull a big number that ORNL can tout. The rest of the codes, which can't effectively be ported to use GPUs, will just run on the CPUs; they'll get work done but won't make good use of the system. Oddly enough, that sounds like what I've heard about Roadrunner...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-3155908228127841862.post-76068996892901992782012-01-09T19:22:24.693-07:002012-01-09T19:22:24.693-07:00@Daniel - thanks!
There's no question that Nv...@Daniel - thanks!<br /><br />There's no question that Nvidia certainly has a good market in ARM chips, including Tegra, and that won't go away any time soon.<br /><br />Unfortunately, volumes on ARM chips don't really help Tesla and Tesla-like GPGPUs. That's a different design point, and doesn't share much if any silicon. <br /><br />They surely will re-use their ARM cores in their new Project Denver HPC offerings. However, the big SIMD/SIMT whomper also on that chip won't, in the future, have a high-volume counterpart to juice its volumes, and that's a significant design effort.<br /><br />I happened to speak with Bill Daly, Nvidia CTO, a few months ago and brought up this point. He basically hoped the low end didn't go away too soon.Greg Pfisterhttps://www.blogger.com/profile/12651996181651540140noreply@blogger.comtag:blogger.com,1999:blog-3155908228127841862.post-21498527728362010042012-01-09T19:10:48.470-07:002012-01-09T19:10:48.470-07:00@Jeff - Aargh! Can't believe I didn't see ...@Jeff - Aargh! Can't believe I didn't see that one. Thanks!Greg Pfisterhttps://www.blogger.com/profile/12651996181651540140noreply@blogger.comtag:blogger.com,1999:blog-3155908228127841862.post-13466571115602221602012-01-09T18:53:11.736-07:002012-01-09T18:53:11.736-07:00The Intel slide about "Experience with Knight...The Intel slide about "Experience with Knights Ferry... unparalleled productivity". I find the wording choice quite amusing. :-)Jeff Squyreshttp://blogs.cisco.com/performance/noreply@blogger.com