

Memristor-based non-volatile memory matches DRAM performance - azernik
http://www.bbc.co.uk/news/technology-16725529

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sschueller
Very interesting video on the memristor. Long but worth it:
<http://www.youtube.com/watch?v=bKGhvKyjgLY>

~~~
sceadu
<http://www.youtube.com/watch?v=QFdDPzcZwbs>

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rcthompson
It's still not a replacement for DRAM, though. The article says it can only
take a million rewrites before failing. Depending on what a computer is doing,
I'll bet the main memory can easily hit that limit in days to weeks.

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kondro
It is a replacement for SSD, not RAM (at least for now). Imagine your
permanent storage being as fast as your RAM.

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Leynos
Do you think this will be a driving impetus for the move from SATA to PCI
Express connected backing stores in consumer hardware?

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archivator
Is that really a possibility? I assumed the 6 Gb/sec (as Wikipedia claims) for
SATA 3 would be sufficient bandwidth for any drive storage.

I'll admit, I've not followed this sort of hardware closely but my
understanding was that SATA is set on its own track, apart from the other
buses like PCI and USB.

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jws
DDR-3's bandwidth is about 20 times SATA-3's.

I'm sure people will make SATA SSD's.

There is an architecture revolution to be had, but it isn't as easy carving
off a high speed bus from the CPU and turning your database speed up to a
factor of 20.

If the write lifetime is a million writes, at 10ns/write you can burn that up
in a millisecond.[1]

Maybe you trust your server hardware to last for three years.[2] You get about
38 writes per hour. I hope you aren't syncing a critical chunk of data once a
minute.

So you have an insanely fast, nonvolatile store, but you can't just write to
it willy-nilly. Let the engineering begin! (I'm sure it has for some people.)

\--

[1] Malware can be expensive in a hurry. A couple quick loops and you can ruin
1000 blocks/second.

[2] If you have less than a few dozen servers you end up playing quality
roulette. You have no idea which models from which vendors are going to hold
up, so you make a guess based on reputation and price. Sometimes you are
right, sometimes you are wrong. Sometimes you have a 50% mortality in 6
months. When you get a model that works well, by the time you know it lasts,
you can't buy it any more. My strategy was always to buy a batch, run them in
non-critical positions for 6 months to screen for early failures, if they were
good, move the critical functions to them, but then get off of them before the
age related failures begin. Three years was about my limit.

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bwarp
This is the next wave of technology. It solves so many fundamental problems. I
can't wait to have a few GiB of MRAM in a workstation.

Load/store architectures may go away due to this. Imagine 32Gb of CPU
registers.

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justincormack
It only said it wad RAM speed, not register or cache speed. There are speed of
light constraints in the memory hierarchy too surely?

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bwarp
A memristor is a smaller and simpler component than once register cell. Due to
this, leakage and speed of light are less of an issue than the current
techology. I wouldn't expect replacement for a decade though.

~~~
haberman
That may be, but OP was talking about having 32 Gb of registers and obsoleting
load/store instructions. Current technology doesn't have 32 Gb of SRAM in
registers, it has less than 1k. Even if the cost of SRAM wasn't an issue, I
would be surprised if you could increase the size of the register file by
30,000,000x while maintaining the same latency and throughput characteristics.

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bwarp
I was the the OP. The CPU spends a lot of time moving shit around rather than
doing work.

My point is to remove the distinction between the register file and the main
memory so that the entire CPU's working set is linear and no copies are
required, therefore drastically increasing speed.

When you do this, you lose all the cache control latency and context switch
overhead, resulting in a much smaller and faster core, leaving plenty of space
for 32Gb on die :)

No existing architectures will do this as they rely on the memory hierarchy.
I'm talking about a new architecture.

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toddh
What will that new architecture look like? ... Since I can't seem to reply to
your comment...so an 8 bit processor :-) It would be interesting to pair this
with the new 100 core chips.

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bwarp
Like zero page in the 6502.

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cs702
Memristors will have a major impact on hardware architecture in the near to
medium term. They promise permanent storage not just without the costs imposed
by SSD (much slower performance than DRAM), but also random access without the
costs imposed by hard drives (variable seek times depending on how data
happens to be laid out on physical discs).

IMHO the impact on software architecture is likely to be much less pronounced
at first, because software ecosystems -- OS kernels, libraries, utilities,
applications, etc. -- can evolve only gradually over a period of many years.
Consider that Ken Thompson and Dennis Ritchie reportedly created the /usr
directory because they ran out of space on a 1.5MB hard disk (!) more than 40
years ago (!), yet we're still living with this directory ( see
[http://lists.busybox.net/pipermail/busybox/2010-December/074...](http://lists.busybox.net/pipermail/busybox/2010-December/074114.html)
).

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vsviridov
No more RAM chip freezing to extract the encryption keys for Mr. Government
Man...

~~~
simias
This is actually a valid point, most modern encryption schemes rely on the
fact that the RAM can't be dumped easily.

I guess you could keep at least some volatile memory for storing sensitive
information such as encryption keys. Of course unless the rest of the MRAM is
encrypted you may indeed leak potentially sensitive data.

Maybe dedicated hardware could encrypt/decrypt the RAM contents on the fly
when the CPU or the devices access it, but it sounds costly.

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wazoox
Processor cache could easily hold the encryption keys. Now that memory
controllers are integrated to modern CPUs, this could be achieved quite easily
when revamping the architecture, adding a couple of special instructions.

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4ad
No new instructions necessary: <http://www1.informatik.uni-erlangen.de/tresor>
.

~~~
simias
Interesting link. However it doesn't solve the security issues caused by non-
volatile unencrypted system memory. I guess custom hardware could
encrypt/decrypt the data going trough the memory controller on the fly.

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JumpCrisscross
_"At present, the endurance of DRAM is effectively a lifetime of usage"_

Liked the article, but that's a self-referencing statement

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AndrewDucker
It means the lifetime of the system it's placed in. DRAM will last until
you've thrown away all of the other bits of your system.

