This document describes the "Zeppelin" system-on-a-chip designed for multi-chip architectures. Key aspects include an 8-core "Zen" CPU complex, AMD Infinity Fabric interconnect, memory and I/O capabilities. The chip is designed for use in both single-die desktop and multi-die server configurations to provide scalability across markets using the same underlying SoC design.

1. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 1 of 29
“Zeppelin”: an SoC for
Multi-chip Architectures
Noah Beck1, Sean White1, Milam Paraschou2, Samuel Naffziger2
1AMD, Boxborough, 2AMD, Fort Collins
Presented at ISSCC 2018

2. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 2 of 29
Outline
▪ Design Goals for the System-on-a-Chip codenamed “Zeppelin”
▪ SoC Architecture
▪ Core Complex codenamed “Zen”
▪ AMD Infinity Fabric (IF)
▪ I/O Capabilities, I/O muxing
▪ Floorplan and Packaging
▪ Results

3. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 3 of 29
“Zeppelin” SoC Goals
Design a System-on-a-Chip Solution for scalability
across the Server market
▪ 4-die multi-chip module (MCM) for Server in new
infrastructure
▪ Same SoC suitable for High-End Desktop
– 1-die Desktop in existing AM4 infrastructure
– 2-die MCM High-End Desktop in new infrastructure

4. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 4 of 29
“Zeppelin” Die Functional Overview
▪ Compute
– 8 “Zen” x86 cores
– 4MB total L2 cache
– 16 MB total L3 cache
▪ Memory
– 2 channel DDR4 with ECC
– 2 DIMMs/channel and
up to 256GB/channel
▪ Integrated I/O
– Coherent and control Infinity Fabric links
– 32 lanes high-speed SERDES
– 4 USB3.1 Gen1 ports
– Server Controller Hub (SPI, LPC, UART, I2C, RTC, SMBus)
IFIS/PCIe® IFOP IFOP
Zen
Zen
Zen
Zen
L3
Zen
Zen
Zen
Zen
L3
IFOP IFIS/PCIe/SATAIFOP
DDR
DDR

5. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 5 of 29
Chip Architecture
Infinity Fabric
Scalable Data Fabric
plane
IFIS/PCIe®
IFIS/PCIe/SATA
IFOP IF SCF
SMU
CAKE CAKE CAKE
PCIe Southbridge
IO Complex
SATA PCIe
CCM
CCX
4 cores +
L3
CAKE
CAKE
IFOP
CCX
4 cores +
L3
CCM
IFOP
DDRDDRIFOP
IOMS
CAKE UMC UMC

6. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 6 of 29
CCX: CPU Complex
▪ 4 cores with L1/L2 caches,
plus shared L3 cache
▪ “Zen” core described in
[Singh ISSCC17]
– L1 Instruction Cache 64KB,
4-way associative
– L1 Data Cache 32KB,
8-way associative
– L2 Cache 512KB,
8-way associative
– 2 threads per core
▪ L3 cache 8MB, 16-way associative, shared by all four cores
CORE 3
CORE L3M
1MB
L
3
C
T
L
L
2
C
T
L
L2M
512K
L3M
1MB

7. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 7 of 29
▪ Fast private L2 cache,
12 cycles
▪ Fast shared L3 cache,
35 cycles
▪ L3 filled from L2 victims
of all four cores
▪ L2 tags duplicated in L3 for
probe filtering and fast cache transfer
▪ Multiple smart prefetchers
▪ 50 outstanding misses from L2 to L3 per core
▪ 96 outstanding misses from L3 to memory
“Zen” Cache hierarchy
32B
fetch
32B/
cycle
CORE 0
32B/
cycle
2*16B
load
8M L3
I+D
Cache
16-way
32K
D-Cache
8-way
64K
I-Cache
4-way
512K L2
I+D
Cache
8-way
1*16B
store
32B/
cycle
32B/
cycle

8. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 8 of 29
AMD Infinity Fabric: Scalable Data Fabric
SDF Transport Layer CAKE
IFIS or
IFOP to
off-chip
IOMS
IO
Complex
CCM
CCX
CCM
CCX
UMC
DDR4
UMC
DDR4
I/O Master/Slave
Unified Memory
Controller
Coherent AMD
SocKet Extender
IF Inter-
Socket SerDes
IF On-Package
SerDes
Cache-Coherent Master
Core Complex

9. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 9 of 29
SDF Local Memory Access
SDF Transport Layer CAKE
IFIS or
IFOP to
off-chip
IOMS
IO
Complex
CCM
CCX
CCM
CCX
UMC
DDR4
UMC
DDR4
Latency to local memory: ~90ns
* See Endnotes for additional system configuration details

10. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 10 of 29
SDF Die-to-Die Memory Accesses
SDF Transport Layer CAKE IFOP
CCM
CCX
CCM
CCX
UMC DDR4
Latency to other memory
within socket: ~145ns
CAKEIFIS
CAKE
SDF Transport
Layer
Latency to memory
attached to other socket
(single hop): ~200ns
IFOP
* See Endnotes for additional system configuration details
UMCDDR4
CAKE
SDF Transport
Layer
IFIS
Other socket
die
Same package
die

11. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 11 of 29
▪ Low-swing, single-ended data for ~50% of power of an equivalent
differential driver
▪ Zero power driver state
during logic 0 transmit
– Transmit/receive
impedance termination to
ground while driver pullup
is disabled
– Also applied during link idle
▪ Data bit inversion
encoding saving 10%
average power per bit
2pJ/bit IFOP SerDes

12. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 12 of 29
Hierarchical Power Management
▪ System Management Unit (SMU) uses
IF Scalable Control Fabric (SCF) plane
▪ SCF: single-lane IFIS SerDes link for
chip-to-chip or socket-to-socket
▪ SMU calculation hierarchy for voltage
level control, C-State Boost, thermal
management, electrical design current
management
– Local chip SMU fast loop
– Master chip SMU slower loop
Die 2
Die 1
Die 3
Die 0
SMU
SMU
SMU
Master
SMU
To other socket

13. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 13 of 29
IO Subsystem & Muxing
▪ 32 lanes multi-protocol I/O
– PCIe, IFIS: two 16-lane links
– PCIe link bifurcation:
max 8 devices per 16-lane link
– SATA: 8 lanes of bottom link
▪ Supports multiple market
segments
▪ Muxing support adds
<1 channel clock latency to IFIS
16-lane link
x16
x16
x8 x8
x4 x4 x4 x4
x2 x2 x2 x2 x2 x2 x2 x2
x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1
x2 x2 x2 x2 x2 x2 x2 x2
x4 x4 x4 x4
16-lane link
x8 x8
x16
x16
IFIS
PCIe
SATA
x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1 x1
x1 x1 x1 x1 x1 x1 x1 x1
I/O
CCX CCX
DDR I/O

14. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 14 of 29
Chip Floorplanning for Package
▪ DDR placement on one die edge
▪ Chips in 4-die MCM rotated 180°,
DDR facing package left/right edges
▪ Package-top Infinity Fabric pinout
requires diagonal placement of IFIS
▪ 4th IFOP enables routing of high-
speed I/O in only four package
substrate
layers
I/O
CCX CCX
DDR I/O

15. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 15 of 29
DDR+IFOP Package Routing
▪ Vertical and Horizontal IFOP: 2 layers each
▪ Diagonal IFOP: 1 layer each
▪ DDR channel: 1 layer each
Layer A Layer B
I/ODDR
Die2
CCX
CCX
I/O
DDR
Die1
CCX
CCX
I/O
I/ODDR
Die3
CCX
CCX
I/O
DDR
Die0
CCX
CCX
I/O
I/OI/O

16. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 16 of 29
DDR+IFIS Package Routing
▪ DDR channel: 1 layer each
▪ IFIS links: 2 layers each Layer C Layer D
I/ODDR
Die2
CCX
CCX
I/O
DDR
Die1
CCX
CCX
I/O
I/ODDR
Die3
CCX
CCX
I/O
DDR
Die0
CCX
CCX
I/O
I/OI/O

17. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 17 of 29
MCM Versus Single-Chip Design
▪ 4-die MCM package: 852mm2 of silicon (4 * 213mm2)
▪ Large single-chip design:
– ~10% area savings: 777mm2 (near reticle size limit)
– Manufacturing/test cost: ~40% higher
– Full 32-core yield: ~17% lower
– Full 32-core cost: ~70% higher
▪ High-yielding multi-chip assembly process
– Achievable based on internal production data
– Die frequency matching using on-die frequency sensors

18. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 18 of 29
MCM Package Achievements
▪ 4094 total LGA pins
▪ 58mm x 75mm organic substrate
▪ 534 IF high-speed chip-to-chip nets
– Over 256GB/s total in-package bandwidth
▪ 1760 high-speed pins
– Over 450GB/s total off-package bandwidth

19. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 19 of 29
More MCM Package Achievements
▪ ~300µF of on-package cap
▪ ~300A current
▪ Up to 200W TDP
Core supply pins, 180A
Uncore supply pins, 65A
1.2Vsupplypins,30A
1.2Vsupplypins,30A

20. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 20 of 29
MCM Core Voltage Variation
▪ Per-core measurements shown
– +/-25mV accuracy with max power
workload
▪ Per-core ring oscillators
– Calibrated for temperature and voltage
– Min/max voltage sampled 470M/s
▪ Static differences compensated by
per-core LDOs
▪ Dynamic differences mitigated by
clock stretcher, DPM states
I/ODDR
Die 2
I/O
DDRDDRDDR
+10.8
+10.8
+7.3
+14.4
+8.9
+12.5
-5.0
-20.9
I/ODDR
Die 1
I/O
I/O
I/O
DDRDDRDDR
+10.5
+10.9
+10.9
-6.5+25.1
+14.1
+7.4
+14.3
I/ODDR
Die 3
I/O
I/O
I/O
DDRDDR
-9.5
-3.0
-3.0
+3.8
-6.4
-13.1
-16.4
-25.7
I/ODDR
Die 0
I/O
I/O
I/O
DDR
-7.3
+6.5
-6.6
-20.1-7.3
-7.3
-9.7
-0.2
* See Endnotes for additional system configuration details

21. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 21 of 29
Core Voltage Measurements
▪ Measured data shows
excellent tracking of per-
core voltage from the
digital LDO with mV-
accurate target voltage
▪ Power savings through
per-core voltage
optimization
* See Endnotes for additional system configuration details

22. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 22 of 29
4-Chip EPYC Package
▪ 128 lanes can be used as PCIe
– Attach six 16-lane accelerator cards
to a single socket
▪ 8 DDR4 channels
NIC
16 DIMMs
Memory
8 Drives
Single Socket AMD EPYCTM System
64 lanes High-speed I/O
I/O
Die2
CCX
CCX
I/O
DDR
Die1
CCX
CCX
I/ODDR
I/O
Die3
CCX
CCX
I/O
DDR
Die0
CCX
CCX
I/ODDR
I/OI/O
64 lanes High-speed I/O
4 Channels
DDR4
4 Channels
DDR4

23. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 23 of 29
Dual 4-Chip EPYC Packages
Dual Socket AMD EPYCTM System
128 lanes High-speed I/O
I/O
Die2
CCX
CCX
I/O
DDR
Die1
CCX
CCX
I/O
DDR
Die0
CCX
CCX
I/O
DDR
I/OI/O
4 Channels
DDR4
4 Channels
DDR4
I/O
Die2
CCX
CCX
I/O
DDR
Die1
CCX
CCX
I/O
DDR
Die0
CCX
CCX
I/O
DDR
I/OI/O
4 Channels
DDR4
4 Channels
DDR4
Die3
CCX
CCX
I/O
DDRI/O
I/O
Die3
CCX
CCX
I/O
DDR

24. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 24 of 29
Single Chip AM4 Package
▪ Socket compatible with
other AMD SoCs for
desktop market
▪ 8 cores / 16 threads
▪ 2 DDR4 channels
▪ 24 PCIe Gen3 lanes
▪ Up to 95W TDP
AMD RyzenTM System
Die
CCX
CCX
I/O
DDR
I/O
24 lanes High-speed I/O
2 Channels
DDR4

25. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 25 of 29
2-Chip sTR4 Package
▪ Socket defined for “Zeppelin”
SoC and compatible with future
designs
▪ 16 cores / 32 threads
▪ 4 DDR4 channels
▪ 64 PCIe Gen3 lanes
AMD RyzenTM ThreadripperTM System
32 lanes High-speed I/O
I/O
Die 1
CCX
CCX
I/O
DDR
Die 0
CCX
CCX
I/O
DDR
I/O
32 lanes High-speed I/O
2 Channels
DDR4
2 Channels
DDR4

26. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 26 of 29
Benchmark results
▪ Scalable performance
from single-chip up to
8-chip 2-socket
configuration
* See Endnotes for additional system configuration details

27. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 27 of 29
IFIS/PCIe IFOP IFOP
Zen
Zen
Zen
Zen
L3
Zen
Zen
Zen
Zen
L3
IFOP IFIS/PCIe/SATAIFOP
DDR
DDR
An SoC for Multi-chip Architectures
Mainstream Desktop Performance Server High-End Desktop
Dummy
Dummy

28. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 28 of 29
Acknowledgment
▪ We would like to thank our talented AMD design teams across
Austin, Bangalore, Boston, Fort Collins, Hyderabad, Markham,
Santa Clara, and Shanghai, who contributed on “Zen” and “Zeppelin”
▪ Please check out our demo tonight

29. 2.4: “Zeppelin”: an SoC for Multi-chip Architectures© 2018 IEEE International Solid-State Circuits Conference 29 of 29
Endnotes
AMD, the AMD Arrow logo, and combinations thereof are trademarks of Advanced Micro Devices, Inc. Other product names used in this
publication are for identification purposes only and may be trademarks of their respective companies.
Slides 9, 10:
Latencies assume 2.4GHz CPU core frequency and 1R DDR4-2667 19-19-19 RDIMM; Memory, IFIS, IFOP latencies are dependent on DRAM
clock; Memory latencies include testing overhead (including DRAM refresh).
Slides 20, 21:
Power measurements taken from a SP3 Diesel non-DAP AMD evaluation system, with EPYC rev B1 parts, BIOS revision WDL7405N,
Windows Server 2016, running a Max Power pattern at 2.5GHz core frequency
Slide 26:
AMD RyzenTM 7 1800X CPU scored 211, using estimated scores based on testing performed in AMD Internal Labs as of 30 March 2017.
System config: RyzenTM 7 1800X: AMD Myrtle-SM with 95W R7 1800X, 32GB DDR4-2667 RAM, Crucial CT256M550SSD, Ubuntu 15.10,
GCC –O2 v4.6 compiler suite.
AMD RyzenTM ThreadripperTM 1950X CPU scored 375, using estimated scores based on testing performed in AMD Internal Labs as of 7
September 2017. System config: RyzenTM ThreadripperTM 1950X: AMD Whitehaven-DAP with 180W TR 1950X, 64GB DDR4-2667 RAM,
CT256M4SSD disk, Ubuntu 15.10, GCC –O2 v4.6 compiler suite.
AMD EPYCTM 7601 CPU scored 702 in a 1-socket using estimated scores based on internal AMD testing as of 6 June 2017. 1 x EPYCTM 7601
CPU in HPE Cloudline CL3150, Ubuntu 16.04, GCC -O2 v6.3 compiler suite, 256 GB (8 x 32 GB 2Rx4 PC4-2666) memory, 1 x 500 GB SSD
AMD EPYCTM 7601 scored 1390 in a 2-socket system using estimated scores based on internal AMD testing as of 6 June 2017. 2 x EPYCTM
7601 CPU in Supermicro AS-1123US-TR4, Ubuntu 16.04, GCC -O2 v6.3 compiler suite, 512 GB (16 x 32GB 2Rx4 PC4-2666 running at 2400)
memory, 1 x 500 GB SSD.