CS 294-42: Technology Trends

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CS 294-42: Technology Trends

Ion Stoica (http://www.cs.berkeley.edu/~istoica/classes/cs294/11/)

September 12, 2011

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“Skate where the puck's going, not where it's been” – Walter Gretzky

Processors

MIMD (Multi-Core Processors) – linear increase: two additional cores every two years

SIMD (GPUs) – exponential increase: width double every four years

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SSDs Performance:

Reads: 25us latency Write: 200us latency Erase: 1,5 ms

Steady state, when SSD full One erase every 64 or 128 reads (depending on page

size) Lifetime: 100,000-1 million writes per page

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Rule of thumb: writes 10x more expensive than reads, and erases 10x more expensive than writes

Storage Performance & PriceBwdth (sequential R/W)

Cost/GB Size

HHD 50-100 MB/s $0.05-0.1/GB 2-4 TB

SSD1 200-500 MB/s (SATA)1.5 GB/s (PCI)

$2-4/GB 200GB-1TB

DRAM 10-16 GB/s $12-13/GB 64GB-256GB

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Bwdth: SSD up to x10 than HDD, DRAM > x10 than SSDPrice: HDD x20 less than SSD, SSD x5 less than DRAM

1http://www.fastestssd.com/featured/ssd-rankings-the-fastest-solid-state-drives/

Storage Price Trends RAMs: x2 every ~20 month (http://www.jcmit.com/memoryprice.htm)

1990-2000: x75 decrease 2000-2010: x63 decrease

Disks: x2 decrease every ~2 years SSDs prices dropped faster than disk prices for

last 5 year(http://rogerluethy.wordpress.com/2010/12/07/price-trends-of-hdds-vs-ssds/) But decrease slightly less over last year

6Storage price halves every ~2 years

Hard Drives (25 years ago) IBM Personal Computer/AT (1986)

30 MB hard disk - $500 30-40ms seek time 0.7-1 MB/s (est.)

730-40sec to scan entire disk

Memory (today)

96 GB RAM - $650-800 (ECC RAM) Memory bus speed: 10-16 GB/s

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6-10sec to scan entire memory!

Working Set: RAM Doubling Software (1995)

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Working Set (Today)

When was the last time your experience trashing on your laptop?

Memory growing faster than application’s needs – conjecture

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Today’s memory, yesterday’s disk!

Working Set – Datacenters % of jobs whose full inputs fit in memory (~1 week)

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Memory (GB)

Facebook (% jobs)

Microsoft (% jobs)

Yahoo! (% jobs)

8 69 38 66

16 74 51 81

32 96 82 97.5

64 97 98 99.5

128 98.8 99.4 99.8

192 99.5 100 100

256 99.6 100 100Nearly all jobs’ inputs fitting in main memory in near future?

(Ganesh Ananthanarayanan)

(Random) Thoughts Today’s disks, yesterday’s tapes [John Ousterhout]

Today’s memory, yesterday’s disk? Or should be today’s SSDs, yesterday’s disks? SSDs not great for caches (due limited writes) Perfect for archival though and GFS-like filer systems ;-)

In-memory computation not enough for interactive workloads Parallelism only way out if need to touch a lot of data

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(Random) Thoughts (cont’d) Today’s servers in Hadoop clusters: 10-12 disks

Up to 1GB/s bwdth How to take advantage of this?

GPU use will only increase: faster increase in processing power than CPUs Need better support for virtualization What to do about memory bwdth?

For data intensive apps, locality will continue to be critical

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Predictions??

Memory the new disk Working sets of more and more apps will fit in memory

SSDs will become the new tape (archival)

GPUs: main driver for increasing processing power Will be integrated in the main processor

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