New Network Design Exploits Cheap, Power-Efficient Flash Memory

jan_jes writes: The researchers at MIT were able to make a network of flash-based servers competitive with a network of RAM-based servers by moving a little computational power off of the servers and onto the chips that control the flash drives. Each server connected to a FPGA and each FPGA, in turn, was connected to flash chips and to the two FPGAs nearest it in the server rack. As it is connected to each other, they created a very fast network that allowed any server to retrieve data from any flash drive. Finally, the FPGAs executed the algorithms that preprocessed the data stored on the flash drives.

Comments

FPGA is just gimmicked flash

[Tough Love]

FPGA is just gimmicked flash sandbagged with a liberal topping of patents. The fundamental patents are getting long in the tooth, keep an eye on those expiry dates. See the obvious connection with OP.

Re: FPGA is just gimmicked flash

[Anonymous Coward]

You should do a search on fpga. You clearly dont know what it is.

Re:FPGA is just gimmicked flash

[TomGreenhaw]

Huh? Field Programmable Gate Arrays allow for redefinable digital logic whose function is limited by the internal signal propagation delays. This allows digital functions to performed very quickly. Compare this to a program that has to process a bunch of instructions to perform logical operations - very flexible but very slow in comparison. I don't understand why you equate digital logic to non-volatile memory arrays.

Re:FPGA is just gimmicked flash

[Dutch Gun]

I don't understand why you equate digital logic to non-volatile memory arrays.

You're simply underestimating the propensity of some people to proudly display their ignorance to the world.

Re:FPGA is just gimmicked flash

[squiggleslash]

This comment reminded me a little of this Wondermark comic.

Re:FPGA is just gimmicked flash

[JustAnotherOldGuy]

Lol, that's beautiful. If I had mod points, they'd be yours.

Re:FPGA is just gimmicked flash

[gweihir]

Only on an abstraction level so high that it is not useful anymore. Sure, FPGA these days is flash-backed these days (used to be EEPROM backed) with the logic-cells actually being RAM-backed and loaded on power-up from FLASH, but storing data and storing logic-configuration is a bit different in most circumstances.

Re:FPGA is just gimmicked flash

[jones_supa]

FPGA is just gimmicked flash sandbagged with a liberal topping of patents. The fundamental patents are getting long in the tooth, keep an eye on those expiry dates. See the obvious connection with OP.

You could make a great character in a Dilbert comic.

Re:FPGA is just gimmicked flash

[Tough Love]

You're simply underestimating the propensity of some people to proudly display their ignorance to the world.

Indeed. Go here. Then read: Conguration Cell Technology: FLASH

Re:FPGA is just gimmicked flash

[Tough Love]

Ah, somebody who actually has a clue. (But drew the wrong conclusion anyway.)

Re:FPGA is just gimmicked flash

[Tough Love]

Heh, that's amusing considering the zero content nature of your reply, coupled with supreme confidence in the pure, unadulterated wit of it. I guess there's a dilbert comic in there somewhere, but not starring me.

Re:FPGA is just gimmicked flash

[JDevers]

OK, explain to us how FPGA and Flash ROM are the same thing.

Re:FPGA is just gimmicked flash

[gweihir]

"Wrong conclusion" as in "does not agree with you"? Not very mature.

And no, the actual logics functionality of FPGAs is _not_ rendered by FLASH cells or even the more modern RAM cells. They just provide the interconnect matrix and the logic-cell internal connections, _not_ the logic.

Methinks the clue is very absent from your view of things.

Re:FPGA is just gimmicked flash

[gweihir]

I think this person may look-up table implemented logic (where the configuration is in the bits stored in the table) and gate-array implemented logic (where the configuration is in the connections between the gates and the config bits statically drive "switches" sitting in the connections).

Seems also to be a classic case of "incompetent and unaware of it" as the mere name Field Programmable Gate Array rather strongly says it is not the look-up table based thing, but the gate array thing.

Re:FPGA is just gimmicked flash

[Dutch Gun]

I should have also predicted that you'd double-down on that statement rather than attempting to educate yourself. Did you just see that flash memory was mentioned in an FPGA-related document without actually understanding the context? Because it sure looks like it to me.

Here, I've got a PDF of my own to show you. This one explains quite clearly that there are multiple ways to store configuration data for an FPGA, and that flash-based memory is only one of several options. I'll summarize in the hopes that you or someone else will learn something even without reading the link.

FPGAs are essentially a set of configurable logic circuits, and this obviously requires a set of configuration data to operate as designed. The higher-level nature of the logic circuits makes FPGAs more efficient than a general-purpose CPU for some specialized types of tasks. There are several ways to apply that configuration data on a device:

* Some FPGAs use flash memory or a master computer as a permanent external store, but use SRAM to maintain the internal configuration state. These devices need to be configured after power-up by the external storage (whether flash or something else), and the SRAM needs to be powered to maintain state.

* Some devices use flash memory internally to maintain the configuration state, rather than as a two-step process.

* Some devices uses anti-fuse circuits to maintain configuration state. These devices, once programmed, can't be altered. No flash or other memory is needed for these types, as the circuitry is essentially physically altered in place with the initial programming.

So, in two out of three commonly-used cases, flash memory isn't even used in the FPGA itself. This isn't even counting the early models that could reset their EPROM-based configuration with an ultraviolet light through a quartz window on the chip itself.

Seriously, just admit when you're wrong.

Re:FPGA is just gimmicked flash

[jones_supa]

You're simply underestimating the propensity of some people to proudly display their ignorance to the world.

Indeed. Go here. Then read: Conguration Cell Technology: FLASH

The Flash chip is typically just a helper chip outside the FPGA. The logic configuration is transferred from the Flash to the FPGA every time when the system is started. But the general concept of FPGA is not about Flash. The general concept of FPGA is about a type of digital logic which can be changed easily.

Re:FPGA is just gimmicked flash

[jones_supa]

Well, maybe we roasted you a bit too much. :) Sorry about that.

Re:FPGA is just gimmicked flash

[LifesABeach]

The one thing that comes to mind is, "Could I replicate the findings?" What would I need?

Re:FPGA is just gimmicked flash

[Anonymous Coward]

(awww... that is a mesh computer model that has been around for a while... I wanted to build one... where can I get one now?)

FPGA? Why not a cheap quad core ARM chip?

[WittyName]

Through in 4 gigs of ram, too!

WOW! IBM Tech from the 80's have been discovered

[Anonymous Coward]

Go back and look at an AS/400, iSeries, i5 and now called IBM i,

Biggest machine I worked on, 32 cores and 3/4TB of ram. And that was still ovly 1/2 as big it could be. But that 3/4TB was not the total ram in the machine, it had IOPs and IOAs that oversaw the the disk drives. Those processors had large ram and were basically fast and faster cache. So our machine with 900 drives in multiple raid-6 groupings (IOPs) with multi-grouping in IOA, acted as a 900 drive raid-0 (stripe) to main core. So reading a file sequencially all the drives will start suppling data first data in 50ms... but then the rest was "just there". Processing 4 billion row history files was easy.

Re:FPGA? Why not a cheap quad core ARM chip?

[gstoddart]

Well, I actually wonder if this isn't something new.

So, think about it, because (I think) this kind of extends a Von Neumann architecture.

âoeBut there may be many applications that can take advantage of this new style of architecture. Which companies recognize: Everybodyâ(TM)s experimenting with different aspects of flash. Weâ(TM)re just trying to establish another point in the design space.â

It gives you a larger degree of parallelism because all the little doohickies are using their local storage to do some of your tasks.

To me it sounds like they've created something which helps with parallelism on huge data sets.

My guess is your cheap quad core isn't as cheap or suited to these tasks as you think.

Very similar to the EMC Isilon...

[mlts]

The EMC Isilon is a cluster of FreeBSD nodes with completely customized filesystem on top. All the nodes are connected to each other by Infiniband, and redundancy is built into OneFS.

I'm visualizing this as someone adding FPGA cards to Isilon nodes, and installing SSDs instead of the usual HDDs in the array. Innovative, but this isn't revolutionary by any means.

Re:Very similar to the EMC Isilon...

[gstoddart]

Big slow cheap with low power consumption;

Flash memory -- the type of memory used by most portable devices -- could provide an alternative to conventional RAM for big-data applications. It's about a tenth as expensive, and it consumes about a tenth as much power.

The problem is that it's also a tenth as fast. But at the International Symposium on Computer Architecture in June, MIT researchers presented a new system that, for several common big-data applications, should make servers using flash memory as efficient as those using conventional RAM, while preserving their power and cost savings.

The researchers also presented experimental evidence showing that, if the servers executing a distributed computation have to go to disk for data even 5 percent of the time, their performance falls to a level that's comparable with flash, anyway.

So, power saving, good performance, and cheaper.

The world hasn't changed, but for a specific kind of problem, this is kind of interesting. This sounds like they've made huge scale computing cheaper for some classes of problem.

I bet the people who solve those problems will care.

Original NUMA work was similar

[Anonymous Coward]

The initial academic work to build clusters sharing memory were very similar. They turned into the more modern concepts of NUMA and Snoopy. It is a modification to Von Neumann, but in general this is the way forward now that flash drives are a minimal time hit. It is more about removing unneeded older technology and simplifying the model. Removing some caches, controllers, and drives by using a faster 'memory' while still getting massive storage.

FPGAs often DO have Arm inside

[Anonymous Coward]

Well FPGAs often do throw in an ARM core or 4 these days:

https://en.wikipedia.org/wiki/Field-programmable_gate_array

e.g. the A Xilinx Zynq-7000 includes a Dual Core Cortex A9 on the chip.

Logic gates are fine, but sometimes you just need some serial execution of code!

Yes but...

[Anonymous Coward]

Can it run Linux?

Re:Yes but...

[Anonymous Coward]

If the project allows it, going with FPGAs is waaay more efficient than running Linux. Even more so if you can make those chips as native ASICs.

Re:FPGA? Why not a cheap quad core ARM chip?

[JonSchell]

Because general purpose processors are slower than a specific purpose module in an FPGA could be. Cheap is not an important consideration in this case.

PHOENIX meets The Donald Tomorrow

[Anonymous Coward]

Be there or be a democrat nerd.

Re:WOW! IBM Tech from the 80's have been discovere

[redwraith94]

Wow ... No solid states? Sucks to be you, bro!

cheap if you get your FPGAs for free

[YesIAmAScript]

The article explains how it's cost effective and they uses FGPAs contributed by their sponsors.

If they had sponsors to give them free RAM somehow I imagine that would have tipped the price comparison the other direction.

Re:cheap if you get your FPGAs for free

[viperidaenz]

Once you're got a large enough demand, you can throw away the FPGA's and use custom silicon.
That would lower the power consumption even further.

Re:cheap if you get your FPGAs for free

[Anonymous Coward]

Once you get a large enough demand, you can build a ram based cluster that meets the spec. Or you can continue to ignore the 3 week lead time of setting up a single purpose fpga to save a couple hours of disk thrashing. Purposely setting up a memcached farm to not handle the load won't hurt as bad if you use less power? Got it.
I'm not saying I can't imagine a use for this, I'm just saying for any given compute problem, I can build a faster, more fault tolerant cluster that will do the job better. If you want to save power, move to Iceland.

Re:FPGA? Why not a cheap quad core ARM chip?

[Anonymous Coward]

Cheap quad core ARM chips are general purpose and would consume more power than a FPGA. Do you know anything?

Re:FPGA? Why not a cheap quad core ARM chip?

[gweihir]

Simple: That would not produce papers, PhDs and press-statements.

Seymour Cray, call your office

[eric_harris_76]

Moving some processing out of the central processor and into processors that access storage is not exactly new.

But I bet these servers don't look too terribly much like CDC 6000s. (Especially their FPGA parts.)

The article should be an interesting read. Which I will get to soon, now that I've offered an uninformed opinion about TFA and incidentally exposed my geezerhood.

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Re:FPGA? Why not a cheap quad core ARM chip?

[eric_harris_76]

Something along those lines -- in a very different era -- were the CDC 6000 series computers designed by Seymour Cray, and their successors.

One or more central processors did the number crunching and general program logic, and some of the OS, with a bunch of smaller, not-so-bright "peripheral processors" doing I/O and certain low-level OS functions. (How not-bright? They couldn't do division or multiplication except by powers of two, for instance.)

Supposedly, Gene Amdahl, designer of the IBM 360 series machines, later said he wished he'd put more smarts into the channel controllers, in the manner of the CDC machines. Don't have a source. That story might be apocryphal, or at least misremembered in its details.

Why use FPGAs? Bandwidth!

[hamster_nz]

A bottom of the range FPGA - 200 I/O pins, with 216.5 Gb/s for $20.

And the one I have sitting on my desk at the moment has about 500 Gb/s over about 300 pins..

You can't get that on an ARM CPU.