Ncore™ Cache Coherent Interconnect - Arteris · 24/05/2016 · Cache Coherent Interconnect...

Ncore™ Cache Coherent InterconnectTechnology Overview, 24 May 2016

David Kruckemyer

Copyright © 2016 Arteris

Chief Technology Officer Chief Hardware Architect

Craig Forrest

24 May 2016

Contents

○ About Arteris

○ Caches, Cache Coherency and Challenges

○ Introducing Ncore Cache Coherent Interconnect

○ Summary

Copyright © 2016 Arteris 2

Arteris: The on-chip interconnect leaderArteris Product Milestones○ Founded in 2003 to pioneer network-on-chip (NoC) interconnect○ NoC Solution = first released NoC implementation in 2005○ FlexNoC® = second generation Arteris NoC in 2009/2010○ FlexPSI = die-to-die or chip-to-chip parallel interface in 2013○ FlexNoC Resilience Package™ = Functional Safety option in 2014○ FlexNoC Physical™ = Physically aware IP with FlexNoC Version 3 in 2015○ Ncore™ Cache Coherent Interconnect = Heterogeneous cache coherency in 2016.Company○ Headquarters and Engineering Development in Campbell, USA○ Worldwide support offices (USA, France, China, Korea, India, Japan)


Customer Adoption

* Customer data current as of 1 May 2016

Awards

1 6 9 1320

4152

5867

76 79

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

3

Arteris has become the standard for complex and low-power SoCs


Customers shipped > 1B SoCs as of 2015

108 Chips Produced

*Data is cumulative. Design data is customer-reported and subject to change. Data is current as of 1 May 2016.

146 Tape-Outs240 Design Starts

1 5 11 1932

55

99119

140 146

2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

1 4 1120

33

51

79

104 108

2008 2009 2010 2011 2012 2013 2014 2015 2016

1 5 13 26 41

85

128159

190

229 240

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016

4

Arteris Customers:Arteris technology is becoming a standard


Mobility

Automotive, IoT (Internet of Things), Camera & CE (Consumer Electronics)

SSD (Solid State Drive), Networking & Automation

Current as of 1 May 2016

Very LargeSoC Maker

Toshiba Japan System OEM

AutomotiveSoC Maker

Major SSD Vendor

Defense Contractor

Defense Contractor Silicon Foundry Major IP

Provider

Large Drone Maker

Japan Tier 1 SoC Maker

Defense Contractor

Major Auto & CE SoC Maker

Major AutomotiveOEM

Major SSD Vendor

Arteris interconnect IP now covers coherent and non-coherent use cases


Design-Specific Subsystems

GPU Subsystem

3D Graphics

DSP Subsystem (A/V) AES

2D GR.

MPEG

Etc.

FlexNoC® Non-coherent Interconnect

High Speed Wired Peripherals

USB 3USB 2

PHY3.0, 2.0

PCIe

PHY

Ethernet

PHY

Wireless Subsystem

WiFi

GSM

LTE

LTE Adv.

InterChip LinksTM

HDMI

MIPI

Display

PMU

JTAG

I/O Peripherals

Memory Subsystem

Wide IO LP DDRDDR3

PHY PHY

Memory Scheduler

Memory Controller

Arteris Interconnect IP Products

Subsystem InterconnectCRI

CryptoFirewall (PCF+)

RSA-PSSCert.

Engine

Security Subsystem

IP

IP

IP

IP

IP

IP

FlexWay® Interconnect

Application IP Subsystem

IP

IP

IP

IP

IP

IP

FlexWay Interconnect

Ncore™ Cache Coherent Interconnect

CPU Subsystem

A57

L2 cache

A57

A57

A57

A53

L2 cache

A53

A53

A53

6

Contents

○ About Arteris



○ Summary


Modern SoC Design Challenges

○ SCALABILITY: How to scale systems up as the number of coherent agents increases?

○ HETEROGENEITY: How to integrate coherent processing elements using different protocols, different semantics, or having different cache characteristics?

○ SYSTEM INTEGRATION: How to integrate IP that is not cache coherent and achieve better performance?

○ PHYSICAL DESIGN: How to create a cache coherent system that is easily placed on chip?

○ POWER MANAGEMENT: How to optimize power consumption of complex systems?


Why Caches?

○ Caches are small, fast memories tightly coupled to processing elements

○ Reduced average memory latency means higher performance• Temporal locality• Spatial locality

○ High bandwidth due to high frequency and wide interfaces

○ Fewer off-chip DRAM accesses resulting in lower power consumption


Why Cache Coherency?

○ Caches create multiple copies of data• Managing these copies in software is difficult

○ Hardware cache coherency creates the illusion of a flat, shared memory• Caches are invisible to software• Multiple copies are kept consistent

○ But… managing copies in hardware requires a lot of communication• Must check every place there may be a valid copy à Snoop• Snoop filters reduce communication by tracking cache contents


Contents

○ About Arteris



○ Summary


Ncore Cache Coherent Interconnect IP


CPU Cluster

DRAM SRAM

Cache ($)

GPU

Cache ($)… Image

ProcessingDisplay

Processing…

Subsystems

Peripherals

Coherent Agents Non-coherent Agents

Non-coherent Agents

Memory Agents12

Ncore Interconnect Architecture


Non-coherent Subsystem

Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI

Coherent Agent Interface

Cache ($) Cache ($)⋯

⋱⋱

⋯

Coherent Memory Interface ⋯


Coherent Memory Interface

Non-coherent

BridgeProxy C

ache ($)

Non-coherent

BridgeProxy C

ache ($)⋯

13

Coherent Read Example – Cache Hit



Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

Bridge⋯

❷

❸

14


Cache ($)

Consumer

❶

Producer

Coherent Read Example – Cache Misses



Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

Bridge⋯❷

❸

15


Cache ($)

Consumer

❶

Memory

❹

Ncore Benefits

1. True heterogeneous coherency

2. Highly scalable systems

3. Higher performance with non-coherent IP

4. Lower power consumption

5. Easier chip floorplanning


Benefit #1: True heterogeneous coherency

Two features are primarily responsible for enabling Ncore’s unique heterogeneous cache coherency capabilities:

1. Support for multiple coherence models

2. Use of multiple configurable snoop filters to accommodate different cache organizations


Benefit #1: True heterogeneous coherencySupport for heterogeneous coherent agents

○ Cache coherent agents can differ greatly, which increases the difficulty in integrating them into a system-on-chip• Logical – coherence models• Physical – cache organization, transaction table sizes

○ Ncore adapts to each coherent agent’s behavior and characteristics• Coherent agent interfaces adapt individual coherence models to a

generic model using a lightweight messaging layer


Benefit #1: True heterogeneous coherencyCoherent agent interfaces adapt individual coherence models to a generic model



Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

BridgeProxy C

ache ($)⋯

19

Benefit #1: True heterogeneous coherencyWith multiple configurable snoop filters


Non-coherent Domain

Non-coherent Bridge(s)

Proxy Cache ($)

Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




○ Cache coherent agents can have very different behaviors• Cache organization• Coherency models• Workloads

○ Associating caching agents that share common properties with individual snoop filters can consume less die area than a monolithic snoop filter

20

Benefit #1: True heterogeneous coherencyMultiple snoop filters are more area-efficient than one


A

Cache ($)

B

Cache ($)C

Cache ($)

DCache ($)

Multiple snoop filters are smaller: area(Y+Z) < area (X)

Traditional Approach

MonolithicSnoop Filter

(X)

REQ

ABCD

Ncore Approach

REQ

Snoop Filter #1(Y)

Snoop Filter #2

(Z)

ABCD

21

Ncore Benefits







Benefit #2: Highly scalable systemsWith a configurable, modular approach

○ Transaction processing and data bandwidth scaling• Each component can be scaled individually (add or subtract

components)• Ports per component can be scaled individually (add or remove

ports)

○ Why is configurable interconnect superior to fixed-function, centralized controllers?• Meet performance goals without wasted resources• Easily adjust system design as requirements evolve• Build derivative chips based on the same platform


Benefit #2: Highly scalable systemsAdd more components or ports to scale bandwidth

Arteris Confidential 24

Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI


Cache ($)

⋱⋱

⋯

⋯


Cache ($)




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

BridgeProxy C

ache ($)⋯

Cache ($)


Add more components…

…or add more ports

Ncore Benefits







Benefit #3: Higher performance with non-coherent IPUsing configurable proxy caches

Advantages (new and novel)1. Better for sharing data between non-coherent agents and

coherent agents2. Better for sharing data between non-coherent agents

○ Using a proxy cache minimizes communication through DRAM

○ Additional system benefits• Pre-fetch effect – fetch cache lines vs. individual data• Write-gathering benefit – writes accumulated in cache • Optimizes coherent memory accesses


Benefit #3: Higher performance with non-coherent IP Sharing between non-coherent & coherent agentsUsing configurable proxy caches



Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

BridgeProxy C

ache ($)⋯

Consumer Producer

❶

❷

❸

❹

❺

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Benefit #3: Higher performance with non-coherent IP Sharing between non-coherent agentsUsing configurable proxy caches



Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

BridgeProxy C

ache ($)⋯

ConsumerProducer

❶

❷

❸

❹

28

Ncore Benefits







Benefit #4: Lower power consumptionWith multiple clock and voltage domains



Directory

Snoop Filter

Snoop Filter

Snoop Filter

Snoop Filter

CCTI



⋱⋱

⋯




Non-coherent

BridgeProxy C

ache ($)

Non-coherent

BridgeProxy C

ache ($)⋯

30

Ncore Benefits







Benefit #5: Easier chip floorplanningWith a highly distributed architecture


○ Reserve less area for cache coherent interconnect• Place it in existing “white space” routing channels – easier P&R

○ Locate modular Ncore components closer to critical IP – better timing

○ Minimize wiring congestion

Source: Andrei Frumusanu, AnandTech

Hub- and crossbar-based coherent interconnects require significant contiguous reserved die area

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Contents

○ About Arteris



○ Summary


Summary

Ncore™ Cache Coherent Interconnect IP is targeted at heterogeneous SoCs.


○ Scalability○ Configurability ○ Area efficiency○ High performance○ Optimal power consumption

○ Multiple configurable snoop filters

○ Multiple configurable proxy caches

○ Modular distributed architecture

Benefits Major Unique Features

RESULT: Custom-configured interconnect IP that meets exact

system requirements

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Ncore™ Cache Coherent Interconnect - Arteris · 24/05/2016 · Cache Coherent Interconnect...

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