Princeton: Replacing RAM with Flash Can Save Massive Power

[Guest]

To everyone using the phrase "swap": go read the paper if you're curious. The researchers are quite specifically looking for a solution better than using the SSD as swap space, and claim to have found one. They also note that not only are they after than swap, but they also use less write cycles than swap, prolonging the life of the flash.

 

[DRosencraft]

I find the vitriol here from all these armchair researchers to be a little sad.

 

[bucknutty]

I find the vitriol here from all these armchair researchers to be a little sad.

TROLL!

 

[DRosencraft]

TROLL!

I would call the scathing damnation of this idea presented by researchers who have spent a lot of time and energy on an it by people who either haven't bothered reading the article here on Tom's, or the researacher's paper, to be the biggest trolls. I simply wanted to state my disgust at that continued practice. But if you want to call me a Troll, go right ahead.

 

[Guest]

Ram only uses a couple watts, really who cares. You are talking about saving energy from a subsystem that uses very little energy in the first place.

On top of that flash is extremely slow compared to ram. You could save more power by underclocking the cpu, and keeping the fast ram, then you ever could by switching to flash. It would be faster and cheaper as well, and anyone can do it right now if all you want is to reduce a few watts of power at the expense of speed.

This 'tech' makes no sense...

 

[blazorthon]

[citation][nom]rtyrty[/nom]Ram only uses a couple watts, really who cares. You are talking about saving energy from a subsystem that uses very little energy in the first place.On top of that flash is extremely slow compared to ram. You could save more power by underclocking the cpu, and keeping the fast ram, then you ever could by switching to flash. It would be faster and cheaper as well, and anyone can do it right now if all you want is to reduce a few watts of power at the expense of speed.This 'tech' makes no sense...[/citation]

It actually does make sense because much of what you said here is wrong. Sure, RAM doesn't use a whole lot of power in your home computer, but servers that can have over several hundred GB to more than a TB of RAM on many modules can use a lot of power strictly for the RAM. Flash is not necessarily much slower than RAM for reads, although sure, for writes flash can't come close to our system RAM. Flash is also substantially cheaper per GB of each chip than RAM is. Some SSDs might be very expensive, but that's just those SSDs. The flash itself is not really that expensive. It's not cheap, but it's not nearly as expensive as RAM is, especially with very high capacity RAM modules for the 1+TB RAM capacity servers that use extremely expensive modules (16GB-32GB) even compared to other lower capacity server modules (4GB-8GB).

Furthermore, this isn't about completely replacing RAM with NAND flash. This is about complimenting RAM with NAND flash.

 

[twelch82]

I would think wear from very frequent writes would be an issue here?

 

[blazorthon]

[citation][nom]twelch82[/nom]I would think wear from very frequent writes would be an issue here?[/citation]

Maybe, but if they use SLC, it's probably not an issue.

 

[back_by_demand]

[citation][nom]DRosencraft[/nom]I would call the scathing damnation of this idea presented by researchers who have spent a lot of time and energy on an it by people who either haven't bothered reading the article here on Tom's, or the researacher's paper, to be the biggest trolls. I simply wanted to state my disgust at that continued practice. But if you want to call me a Troll, go right ahead.[/citation]
Naysayers gotta Naysay

 

[bspatial]

Can that improve the performance for Crysis?

 

[vittau]

So they have created a flash memory swap partition, genius!

 

[znyari]

Is there any research into lowering SRAM prices? Imagine if our system memories would have the same speed as processor caches and requiring much less power. I bet even the circuitry could be simpler in our processors and motherboards (would we even need L2 cache at that point?)

 

[znyari]

Is there any research into lowering SRAM prices? Imagine if our system memories would have the same speed as processor caches and requiring much less power. I bet even the circuitry could be simpler in our processors and motherboards (would we even need L2 cache at that point?)

 

[znyari]

Is there any research into lowering SRAM prices? Imagine if our system memories would have the same speed as processor caches and requiring much less power. I bet even the circuitry could be simpler in our processors and motherboards (would we even need L2 cache at that point?)

 

[jasonkaler]

[citation][nom]blazorthon[/nom]Read performance per cell of NAND flash is fairly close to DRAM read performance. Write performance is exponentially lower than DRAM, but read performance (arguably more important) is close. Even then, the write perfomrance difference is nothing like the difference between NAND flash and floppy disks.[/citation]

The slowest DDR3 chips are 200 times faster than the fastest NAND chips.

 

[Pherule]

[citation][nom]rtyrty[/nom]You could save more power by underclocking the cpu[/citation]

My i5 already automatically underclocks to 1.6Ghz almost all the time. It turbo boosts to 3.4Ghz on demand (with all 4 cores in use)

 

[blazorthon]

[citation][nom]znyari[/nom]Is there any research into lowering SRAM prices? Imagine if our system memories would have the same speed as processor caches and requiring much less power. I bet even the circuitry could be simpler in our processors and motherboards (would we even need L2 cache at that point?)[/citation]

SRAM can't be made as densely as even DRAM. It's expensive because it can't be mass-produced in as high capacities per chip without very large chips which would still be expensive.

[citation][nom]jasonkaler[/nom]The slowest DDR3 chips are 200 times faster than the fastest NAND chips.[/citation]

Not for random access reads. sequential access, maybe, but that's far less important for this usage. Look at say the Vertex 4. It has extremely low latency even compared to other SSDs, as do several other SSDs that utilize Marvell controllers. It's not even at the limits of Flash's random access times for reads.

 

[meltbox360]

[citation][nom]blazorthon[/nom]It actually does make sense because much of what you said here is wrong. Sure, RAM doesn't use a whole lot of power in your home computer, but servers that can have over several hundred GB to more than a TB of RAM on many modules can use a lot of power strictly for the RAM. Flash is not necessarily much slower than RAM for reads, although sure, for writes flash can't come close to our system RAM. Flash is also substantially cheaper per GB of each chip than RAM is. Some SSDs might be very expensive, but that's just those SSDs. The flash itself is not really that expensive. It's not cheap, but it's not nearly as expensive as RAM is, especially with very high capacity RAM modules for the 1+TB RAM capacity servers that use extremely expensive modules (16GB-32GB) even compared to other lower capacity server modules (4GB-8GB).Furthermore, this isn't about completely replacing RAM with NAND flash. This is about complimenting RAM with NAND flash.[/citation]

Servers are high io environments. There is a reason they run the hard drives in raid 5. Now imagine what would happen to a ssd used as RAM. It would die. Now onto problem number 2. High performance sometimes uses less power because the system spends A LOT less time performing a task and therefore a lot less power overall. Imagine the extra power pulled by the cpu waiting on the ssd vs some ram. It is a lot more than what you would save. Then there is issue number 3 where latency is really important on a server and you should really stick to RAM with ecc and the lot.

 

[blazorthon]

[citation][nom]meltbox360[/nom]Servers are high io environments. There is a reason they run the hard drives in raid 5. Now imagine what would happen to a ssd used as RAM. It would die. Now onto problem number 2. High performance sometimes uses less power because the system spends A LOT less time performing a task and therefore a lot less power overall. Imagine the extra power pulled by the cpu waiting on the ssd vs some ram. It is a lot more than what you would save. Then there is issue number 3 where latency is really important on a server and you should really stick to RAM with ecc and the lot.[/citation]

This isn't about replacing RAM with NAND flash completely, just supplementing it. Something like the RAM caching the flash, but from the article, it seems to be something more complex than that.

 

[meltbox360]

[citation][nom]blazorthon[/nom]This isn't about replacing RAM with NAND flash completely, just supplementing it. Something like the RAM caching the flash, but from the article, it seems to be something more complex than that.[/citation]

I hope it is more complex than swap... Swap really only ever seemed to keep a machine running although very slowly vs crashing normally. Perhaps this is for those machines that would normally run slowly to run faster. My point was this is a bad idea in a server environment imo.

 

[blazorthon]

[citation][nom]meltbox360[/nom]I hope it is more complex than swap... Swap really only ever seemed to keep a machine running although very slowly vs crashing normally. Perhaps this is for those machines that would normally run slowly to run faster. My point was this is a bad idea in a server environment imo.[/citation]

It's much better than resorting to paging files on hard drives. A web server that can have accesses being run mostly on flash and RAM rather than RAM and hard disk storage could increase in performance incredibly, at least from the user's point of view. Supposedly, this is more than mere swap, but the Princeton guys seem to be either be keeping many of the details to themselves or Tom's simply didn't give us enough info that is already publicly available. Either way, a Google search might help.

 

[warpuck]

I didnt grad from a ivy league U, therefore I am too foopid to understand. Lets see AMD processor 95 watts + 2 amd GPUs 100 watts each. So just where was this going? OK 2 sticks of ram barely fast enough to keep up. Maybe going from 8Gb to 80 Gb is the part I am missing. So what I need is 10x more slower RAM?

 

[jewie27]

[citation][nom]oneblackened[/nom]I was just about to ask that, that strikes me as a little worrisome considering flash has a very limited lifespan.[/citation]

this ain't the SAT

 

[blazorthon]

[citation][nom]warpuck[/nom]I didnt grad from a ivy league U, therefore I am too foopid to understand. Lets see AMD processor 95 watts + 2 amd GPUs 100 watts each. So just where was this going? OK 2 sticks of ram barely fast enough to keep up. Maybe going from 8Gb to 80 Gb is the part I am missing. So what I need is 10x more slower RAM?[/citation]

You're not replacing all of the RAM with NAND... Sensationalist, misleading titles aren't what you should try judging this by. NAND flash is being used to supplement the RAM in this technology.

 

[balister]

[citation][nom]oneblackened[/nom]I was just about to ask that, that strikes me as a little worrisome considering flash has a very limited lifespan.[/citation]

MLC yes, SLC, not so much. SLC typically can withstand a factor of 10 more writes than MLC. If you use SLC, it probably wouldn't be an issue. The problem that would then arise if the price as SLC is tyipcally 3 to 4 times as expensive as MLC (compare consumer SSD prices to enterprise SSD prices and you'll see what I mean).