5 ms·
I can't stress how game-changing this is to anyone in super-computing. (The whole direction Intel's been taking for the last ~5 years has been poised for this.)
by iheartmemcache 11y ago
I can't stress how game-changing this is to anyone in super-computing. (The whole direction Intel's been taking for the last ~5 years has been poised for this.) I went into a bit of detail here[1] (n.b. this was pre-Xeon D, the addition of which will only increase performance) for those who are curious.
Right now we're living in a golden age of financially accessible super-computing. We don't need to deal with MPI anymore, we just use RDMA and have Infiniband speed fetches to any machine joined to the cluster[see: MS Paper]. I was working on RELION as a favor to my father and got deeper and deeper into it because my docket was pretty open and it was fascinating. Long story short, I sketched up a test setup with Phi, RDMA (which admittedly wasn't used that much, as the problem set would be characterized by anyone as "embarrassingly parallel") and 10GBit. This is all commodity stuff, and we effectively never touch disk -- I cobbled together 18650's in the rack[see: batt] instead of a UPS with a uC which fires off a 'persist state to disk' message on any power interrupt but other than that it's all RAM and blazing fast. (Side-note: anyone who read the Nature Methods special on all the Cryo-EM stuff may be seeing a paper or two with a few new sets of computational methodologies in the near future ;))
Buyer beware though -- sacrificing clock speed for more cores can end up costing you a lot more overall[2]. Licensing policies have a tendency to change around from version to version, so your perfectly licensed Oracle 11g (lets say it was quantified by the physical chip you throw into the socket) might not have a straight forward upgrade path (now by the number of vCPUs). A lot of clients of mine got burned trying to move from Iron to AWS, only to realize that Oracle licensed per _available CPU_. Fines galore. They ended up downgrading to a previous revision Xeon (i.e. 4th gen E5 MSRP $x,xxx instead of 5th gen E5 MSRP $0,xxx with better performance but more cores). Anyone encountering this problem should keep that trick up their sleeve and find some 1 year old off-lease equipment with less cores but a higher clock speed to keep license compliance and still meet your computational demands. Anyways, yeah the latest and greatest might not be the most economic of choices for this reason[licensing].
[1] https://news.ycombinator.com/item?id=10805087 https://news.ycombinator.com/item?id=10805087
[2] This has so many variables as one can imagine - you can't just go by what people did in 1975 i.e. "this instruction takes x cycles, we can physically count how long our computation will take with a sheet of graph paper" because of pre-fetching, pipelining, cache patterns, the use (or lack of use) of the AVX(2) registers, etc etc.
[3]https://software.intel.com/en-us/articles/intelr-xeon-phitm-coprocessor-february-developer-webinar-qa-responses https://software.intel.com/en-us/articles/intelr-xeon-phitm-...
[MS Paper] http://sigops.org/sosp/sosp15/current/2015-Monterey/printable/227-dragojevic.pdf http://sigops.org/sosp/sosp15/current/2015-Monterey/printabl...
[Batt] As you probably have guessed, I have no formal EE training. I did however rigorously read all of the safety datasheets, use very high quality Panasonics, and strictly conform to the CC-CV guidelines so my fathers lab would not catch on fire. This is probably not the best idea, but it's electrically safe and isolated. It'd pass UL certification.... at least I think ;) [licensing] If you're a corporate entity who is moving into any sort of cloud or onto new hardware, my firm has quite a bit of expertise in licensing compliance when either a) shifting to new hardware, or b) shifting to the cloud, as well as getting your best bang for buck with existing licenses.
- deleted 11y ago[deleted]
- voltagex_ 11y ago>I cobbled together 18650's in the rack[see: batt] instead of a UPS with a uC which fires off a 'persist state to disk' message on any power interrupt How did your tests go with this? I'd totally use a system like this - properly packaged up of course. Li-ion and Li-poly make me nervous.
- iheartmemcache 11y agoI trust it as much as commercial grade APCs I've used in DCs. It definitely cost more in my engineering time than buying an off-the-shelf component, since I spent a lot of time researching it. But I'm a hardware nerd at heart and rarely get to putz around with this kind of stuff, so it didn't really seem like labor to me. The precautions I took were probably overkill but since it wasn't my lab I chose to go pretty overboard. In addition to conforming to the strict charge-discharge guidelines Panasonic thoroughly delineated in their sheets, were to use 1: use "protected 18650's" (actually designated as 19760) which have internal circuitry to keep, say, cheap chinese eBay charge-units from setting peoples house on fire, 2: sourced the batteries from a vendor I've trusted for ages (since the Panasonic 'greens' have such a popular reputation, and knock-offs make it into all sorts of markets including first-tier shops like Amazon and Digikey, I asked my vendor to source directly from Panasonic JP, which he did and provided me with a packing slip). Fear of Li-* is reasonable, and I figure risking permanent damage to ones body and/or life isn't worth the 7 bucks you save buying no-names - go with the 19760's and live life to the fullest! (Pro-tip, the form factor of the 760s are about a mm or 1.2 mm or something longer than unprotected 850s due to the added circuitry -- which I presume is just a PTC thermistor + kill switch, I haven't looked it up though. I'm sure there's a mass difference too if you have access to lab quality scales or are friendly with your local cannibus vendor. Thrown in the case I have a live K-type thermocouple in all 8 of the 1u's (a pair in each rack) with conservative failure policies should temperatures exceed parameters I set. I put put some nice fusing (HRC.. why? because I was already going overkilling and since this wasn't an off-the-shelf component, and I'm not an EE with extensive PDU experience I decided to go safe. (I also consulted with a post-doc buddy of mine who's actively in lithium battery research and after a good chuckle told me the precautions I took were satisfactory.) It came in at around 5k USD for all 8 units with everything, including ~115 a piece for the Hammond 1u's. Each unit can sustain a little under 4.5 kVA which gives more than enough buffer time for a graceful shutdown