High Performance MPI+X Library for Emerging HPC Clusters

High Performance and Scalable MPI+X Library for
Emerging HPC Clusters
Dhabaleswar K. (DK) Panda
The Ohio State University
E-mail: panda@cse.ohio-state.edu
http://www.cse.ohio-state.edu/~panda
Talk at Intel HPC Developer Conference (SC ‘16)
by
Khaled Hamidouche
The Ohio State University
E-mail: hamidouc@cse.ohio-state.edu
http://www.cse.ohio-state.edu/~hamidouc

Intel HPC Dev Conf (SC ‘16) 2Network Based Computing Laboratory
High-End Computing (HEC): ExaFlop & ExaByte
100-200
PFlops in
2016-2018
1 EFlops in
2023-2024?
10K-20K
EBytes in
2016-2018
40K EBytes
in 2020 ?
ExaFlop & HPC•
ExaByte & BigData•

Trends for Commodity Computing Clusters in the Top 500
List (http://www.top500.org)
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Timeline
Percentage of Clusters
Number of Clusters
85%

Drivers of Modern HPC Cluster Architectures
Tianhe – 2 Titan Stampede Tianhe – 1A
• Multi-core/many-core technologies
• Remote Direct Memory Access (RDMA)-enabled networking (InfiniBand and RoCE)
• Solid State Drives (SSDs), Non-Volatile Random-Access Memory (NVRAM), NVMe-SSD
• Accelerators (NVIDIA GPGPUs and Intel Xeon Phi)
Accelerators / Coprocessors
high compute density, high
performance/watt
>1 TFlop DP on a chip
High Performance Interconnects -
InfiniBand
<1usec latency, 100Gbps Bandwidth>Multi-core Processors SSD, NVMe-SSD, NVRAM

Designing Communication Libraries for Multi-Petaflop and
Exaflop Systems: Challenges
Programming Models
MPI, PGAS (UPC, Global Arrays, OpenSHMEM), CUDA, OpenMP,
OpenACC, Cilk, Hadoop (MapReduce), Spark (RDD, DAG), etc.
Application Kernels/Applications
Networking Technologies
(InfiniBand, 40/100GigE,
Aries, and OmniPath)
Multi/Many-core
Architectures
Accelerators
(NVIDIA and MIC)
Middleware
Co-Design
Opportunities
and
Challenges
across Various
Layers
Performance
Scalability
Fault-
Resilience
Communication Library or Runtime for Programming Models
Point-to-point
Communicatio
n
Collective
Communicatio
n
Energy-
Awareness
Synchronizatio
n and Locks
I/O and
File Systems
Fault
Tolerance

Exascale Programming models
Next-Generation Programming models
MPI+X
X= ?
OpenMP, OpenACC, CUDA, PGAS, Tasks….
Highly-Threaded
Systems (KNL)
Irregular
Communications
Heterogeneous
Computing with
Accelerators
• The community believes
exascale programming model
will be MPI+X
• But what is X?
– Can it be just OpenMP?
• Many different environments
and systems are emerging
– Different `X’ will satisfy the
respective needs

• Scalability for million to billion processors
– Support for highly-efficient inter-node and intra-node communication (both two-sided and one-sided)
– Scalable job start-up
• Scalable Collective communication
– Offload
– Non-blocking
– Topology-aware
• Balancing intra-node and inter-node communication for next generation nodes (128-1024 cores)
– Multiple end-points per node
• Support for efficient multi-threading (OpenMP)
• Integrated Support for GPGPUs and Accelerators (CUDA)
• Fault-tolerance/resiliency
• QoS support for communication and I/O
• Support for Hybrid MPI+PGAS programming (MPI + OpenMP, MPI + UPC, MPI + OpenSHMEM,
CAF, …)
• Virtualization
• Energy-Awareness
MPI+X Programming model: Broad Challenges at Exascale

• Extreme Low Memory Footprint
– Memory per core continues to decrease
• D-L-A Framework
– Discover
• Overall network topology (fat-tree, 3D, …), Network topology for processes for a given job
• Node architecture, Health of network and node
– Learn
• Impact on performance and scalability
• Potential for failure
– Adapt
• Internal protocols and algorithms
• Process mapping
• Fault-tolerance solutions
– Low overhead techniques while delivering performance, scalability and fault-tolerance
Additional Challenges for Designing Exascale Software Libraries

Overview of the MVAPICH2 Project
• High Performance open-source MPI Library for InfiniBand, Omni-Path, Ethernet/iWARP, and RDMA over Converged Ethernet (RoCE)
– MVAPICH (MPI-1), MVAPICH2 (MPI-2.2 and MPI-3.0), Started in 2001, First version available in 2002
– MVAPICH2-X (MPI + PGAS), Available since 2011
– Support for GPGPUs (MVAPICH2-GDR) and MIC (MVAPICH2-MIC), Available since 2014
– Support for Virtualization (MVAPICH2-Virt), Available since 2015
– Support for Energy-Awareness (MVAPICH2-EA), Available since 2015
– Support for InfiniBand Network Analysis and Monitoring (OSU INAM) since 2015
– Used by more than 2,690 organizations in 83 countries
– More than 402,000 (> 0.4 million) downloads from the OSU site directly
– Empowering many TOP500 clusters (Nov ‘16 ranking)
• 1st ranked 10,649,640-core cluster (Sunway TaihuLight) at NSC, Wuxi, China
• 13th ranked 241,108-core cluster (Pleiades) at NASA
• 17th ranked 519,640-core cluster (Stampede) at TACC
• 40th ranked 76,032-core cluster (Tsubame 2.5) at Tokyo Institute of Technology and many others
– Available with software stacks of many vendors and Linux Distros (RedHat and SuSE)
– http://mvapich.cse.ohio-state.edu
• Empowering Top500 systems for over a decade
– System-X from Virginia Tech (3rd in Nov 2003, 2,200 processors, 12.25 TFlops) ->
Sunway TaihuLight at NSC, Wuxi, China (1st in Nov’16, 10,649,640 cores, 93 PFlops)

• Hybrid MPI+OpenMP Models for Highly-threaded Systems
• Hybrid MPI+PGAS Models for Irregular Applications
• Hybrid MPI+GPGPUs and OpenSHMEM for Heterogeneous
Computing with Accelerators
Outline

• Systems like KNL
• MPI+OpenMP is seen as the best fit
– 1 MPI process per socket for Multi-core
– 4-8 MPI processes per KNL
– Each MPI process will launch OpenMP threads
• However, current MPI runtimes are not “efficiently” handling the hybrid
– Most of the application use Funneled mode: Only the MPI processes perform
communication
– Communication phases are the bottleneck
• Multi-endpoint based designs
– Transparently use threads inside MPI runtime
– Increase the concurrency
Highly Threaded Systems

• MPI-4 will enhance the thread support
– Endpoint proposal in the Forum
– Application threads will be able to efficiently perform communication
– Endpoint is the communication entity that maps to a thread
• Idea is to have multiple addressable communication entities within a single process
• No context switch between application and runtime => better performance
• OpenMP 4.5 is more powerful than just traditional data parallelism
– Supports task parallelism since OpenMP 3.0
– Supports heterogeneous computing with accelerator targets since OpenMP 4.0
– Supports explicit SIMD and threads affinity pragmas since OpenMP 4.0
MPI and OpenMP

• Lock-free Communication
– Threads have their own resources
• Dynamically adapt the number of threads
– Avoid resource contention
– Depends on application pattern and system
performance
• Both intra- and inter-nodes communication
– Threads boost both channels
• New MEP-Aware collectives
• Applicable to the endpoint proposal in MPI-4
MEP-based design: MVAPICH2 Approach
Multi-endpoint Runtime
Request
Handling
Progress
Engine
Comm.
Resources
Management
Endpoint Controller
Collective
Optimized Algorithm
Point-to-Point
MPI/OpenMP Program
MPI Collective
(MPI_Alltoallv,
MPI_Allgatherv...)
*Transparent support
MPI Point-to-Point
(MPI_Isend, MPI_Irecv,
MPI_Waitall...)
*OpenMP Pragma needed
Lock-free Communication Components
M. Luo, X. Lu, K. Hamidouche, K. Kandalla and D. K. Panda, Initial Study of Multi-Endpoint Runtime for MPI+OpenMP Hybrid
Applications on Multi-Core Systems. International Symposium on Principles and Practice of Parallel Programming (PPoPP '14).

Performance Benefits: OSU Micro-Benchmarks (OMB) level
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Message size
Orig Multi-threaded Runtime
Proposed Multi-Endpoint Runtime
Process based Runtime
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Multi-pairs Bcast Alltoallv
• Reduces the latency from 40us to 1.85 us (21X)
• Achieves the same as Processes
• 40% improvement on latency for Bcast on 4,096 cores
• 30% improvement on latency for Alltoall on 4,096 cores

Performance Benefits: Application Kernel level
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Time(s)
NAS Benchmark with 256 nodes (4,096 cores) CLASS E
Orig
mep
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ExecutionTime
# of cores and input size
P3DFFT
Orig MEP
• 6.3% improvement for MG, 11.7% improvement for CG, and 12.6% improvement for LU on 4,096
cores.
• With P3DFFT, we are able to observe a 30% improvement in communication time and 13.5%
improvement in the total execution time.

• On-load approach
– Takes advantage of the idle cores
– Dynamically configurable
– Takes advantage of highly multithreaded cores
– Takes advantage of MCDRAM of KNL processors
• Applicable to other programming models such as PGAS, Task-based, etc.
• Provides portability, performance, and applicability to runtime as well as
applications in a transparent manner
Enhanced Designs for KNL: MVAPICH2 Approach

Performance Benefits of the Enhanced Designs
• New designs to exploit high concurrency and MCDRAM of KNL
• Significant improvements for large message sizes
• Benefits seen in varying message size as well as varying MPI processes
Very Large Message Bi-directional Bandwidth16-process Intra-node All-to-AllIntra-node Broadcast with 64MB Message
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Message size
MVAPICH2 MVAPICH2-Optimized
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Latency(us)
No. of processes
27%
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Latency(us)
Message size
17.2%
52%

Performance Benefits of the Enhanced Designs
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Bandwidth(MB/s)
Message Size (bytes)
MV2_Opt_DRAM MV2_Opt_MCDRAM
MV2_Def_DRAM MV2_Def_MCDRAM
30%
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300
4:268 4:204 4:64
Time(s)
MPI Processes : OMP Threads
MV2_Def_DRAM MV2_Opt_DRAM
15%
Multi-Bandwidth using 32 MPI processesCNTK: MLP Training Time using MNIST (BS:64)
• Benefits observed on training time of Multi-level Perceptron (MLP) model on MNIST dataset
using CNTK Deep Learning Framework
Enhanced Designs will be available in upcoming MVAPICH2 releases

Outline

Maturity of Runtimes and Application Requirements
• MPI has been the most popular model for a long time
- Available on every major machine
- Portability, performance and scaling
- Most parallel HPC code is designed using MPI
- Simplicity - structured and iterative communication patterns
• PGAS Models
- Increasing interest in community
- Simple shared memory abstractions and one-sided communication
- Easier to express irregular communication
• Need for hybrid MPI + PGAS
- Application can have kernels with different communication characteristics
- Porting only part of the applications to reduce programming effort

Hybrid (MPI+PGAS) Programming
• Application sub-kernels can be re-written in MPI/PGAS based on communication
characteristics
• Benefits:
– Best of Distributed Computing Model
– Best of Shared Memory Computing Model
Kernel 1
MPI
Kernel 2
MPI
Kernel 3
MPI
Kernel N
MPI
HPC Application
Kernel 2
PGAS
Kernel N
PGAS

Current Approaches for Hybrid Programming
• Need more network and
memory resources
• Might lead to deadlock!
• Layering one programming model over another
– Poor performance due to semantics mismatch
– MPI-3 RMA tries to address
• Separate runtime for each programming model
Hybrid (OpenSHMEM + MPI) Applications
OpenSHMEM Runtime MPI Runtime
InfiniBand, RoCE, iWARP
OpenSHMEM Calls MPI Class

The Need for a Unified Runtime
• Deadlock when a message is sitting in one runtime, but application calls the other runtime
• Prescription to avoid this is to barrier in one mode (either OpenSHMEM or MPI) before entering
the other
• Or runtimes require dedicated progress threads
• Bad performance!!
• Similar issues for MPI + UPC applications over individual runtimes
shmem_int_fadd (data at p1);
/* operate on data */
MPI_Barrier(comm);
/*
local
computation
*/
MPI_Barrier(comm);
P0 P1
OpenSHMEM
Runtime
MPI Runtime OpenSHMEM
Runtime
MPI Runtime
Active Msg

MVAPICH2-X for Hybrid MPI + PGAS Applications
MPI, OpenSHMEM, UPC, CAF, UPC++ or Hybrid (MPI +
PGAS) Applications
Unified MVAPICH2-X Runtime
InfiniBand, RoCE, iWARP
OpenSHMEM Calls MPI CallsUPC Calls
• Unified communication runtime for MPI, UPC, OpenSHMEM, CAF, UPC++ available with MVAPICH2-
X 1.9 onwards! (since 2012)
– http://mvapich.cse.ohio-state.edu
• Feature Highlights
– Supports MPI(+OpenMP), OpenSHMEM, UPC, CAF, UPC++, MPI(+OpenMP) + OpenSHMEM, MPI(+OpenMP)
+ UPC
– MPI-3 compliant, OpenSHMEM v1.0 standard compliant, UPC v1.2 standard compliant (with initial support
for UPC 1.3), CAF 2008 standard (OpenUH), UPC++
– Scalable Inter-node and intra-node communication – point-to-point and collectives
CAF Calls UPC++ Calls

OpenSHMEM Atomic Operations: Performance
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Time(us)
UH-SHMEM MV2X-SHMEM Scalable-SHMEM OMPI-SHMEM
• OSU OpenSHMEM micro-benchmarks (OMB v4.1)
• MV2-X SHMEM performs up to 40% better compared to UH-SHMEM

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Time(ms)
Message Size
UPC-GASNet
UPC-OSU
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Time(ms)
Message Size
UPC-GASNet
UPC-OSU 2X
UPC Collectives Performance
Broadcast (2,048 processes) Scatter (2,048 processes)
Gather (2,048 processes) Exchange (2,048 processes)
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Time(us)
Message Size
UPC-GASNet
UPC-OSU
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512
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8K
16K
32K
64K
128K
256K
Time(ms)
Message Size
UPC-GASNet
UPC-OSU
25X
2X
35%
J. Jose, K. Hamidouche, J. Zhang, A. Venkatesh, and D. K. Panda, Optimizing Collective Communication in UPC (HiPS’14, in association with
IPDPS’14)

Performance Evaluations for CAF model
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Message Size (byte)
GASNet-IBV
GASNet-MPI
MV2X
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MV2X
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(ms)
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0 100 200 300
bt.D.256
cg.D.256
ep.D.256
ft.D.256
mg.D.256
sp.D.256
Time (sec)
Get NAS-CAFPut
• Micro-benchmark improvement (MV2X vs. GASNet-IBV, UH CAF test-suite)
– Put bandwidth: 3.5X improvement on 4KB; Put latency: reduce 29% on 4B
• Application performance improvement (NAS-CAF one-sided implementation)
– Reduce the execution time by 12% (SP.D.256), 18% (BT.D.256)
3.5X
29%
12%
18%
J. Lin, K. Hamidouche, X. Lu, M. Li and D. K. Panda, High-performance Co-array Fortran support with MVAPICH2-X: Initial
experience and evaluation, HIPS’15

UPC++ Collectives Performance
MPI + {UPC++}
application
GASNet Interfaces
UPC++
Runtime
Network
Conduit (MPI)
MVAPICH2-X
Unified
communication
Runtime (UCR)
MPI + {UPC++}
application
UPC++ Runtime
MPI
Interfaces
• Full and native support for hybrid MPI + UPC++ applications
• Better performance compared to IBV and MPI conduits
• OSU Micro-benchmarks (OMB) support for UPC++
• Available since MVAPICH2-X 2.2RC1
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Time(us)
GASNet_MPI
GASNET_IBV
MV2-X
14x
Inter-node Broadcast (64 nodes 1:ppn)
J. M. Hashmi, K. Hamidouche, and D. K. Panda, Enabling
Performance Efficient Runtime Support for hybrid
MPI+UPC++ Programming Models, IEEE International
Conference on High Performance Computing and
Communications (HPCC 2016)

Application Level Performance with Graph500 and Sort
Graph500 Execution Time
J. Jose, S. Potluri, K. Tomko and D. K. Panda, Designing Scalable Graph500 Benchmark with Hybrid MPI+OpenSHMEM Programming
Models, International Supercomputing Conference (ISC’13), June 2013
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Time(s)
No. of Processes
MPI-Simple
MPI-CSC
MPI-CSR
Hybrid (MPI+OpenSHMEM)
13X
7.6X
• Performance of Hybrid (MPI+ OpenSHMEM) Graph500 Design
• 8,192 processes
- 2.4X improvement over MPI-CSR
- 7.6X improvement over MPI-Simple
• 16,384 processes
- 1.5X improvement over MPI-CSR
- 13X improvement over MPI-Simple
Sort Execution Time
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Time(seconds)
Input Data - No. of Processes
MPI Hybrid
51%
• Performance of Hybrid (MPI+OpenSHMEM) Sort
Application
• 4,096 processes, 4 TB Input Size
- MPI – 2408 sec; 0.16 TB/min
- Hybrid – 1172 sec; 0.36 TB/min
- 51% improvement over MPI-design
J. Jose, S. Potluri, H. Subramoni, X. Lu, K. Hamidouche, K. Schulz, H. Sundar and D. Panda Designing Scalable Out-of-core Sorting with
Hybrid MPI+PGAS Programming Models, PGAS’14

MiniMD – Total Execution Time
• Hybrid design performs better than MPI implementation
• 1,024 processes
- 17% improvement over MPI version
• Strong Scaling
Input size: 128 * 128 * 128
Performance Strong Scaling
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Hybrid-Barrier MPI-Original Hybrid-Advanced
17%
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Time(ms)
Time(ms)
# of Cores # of Cores

Accelerating MaTEx k-NN with Hybrid MPI and OpenSHMEM
KDD (2.5GB) on 512 cores
9.0%
KDD-tranc (30MB) on 256 cores
27.6%
• Benchmark: KDD Cup 2010 (8,407,752 records, 2 classes, k=5)
• For truncated KDD workload on 256 cores, reduce 27.6% execution time
• For full KDD workload on 512 cores, reduce 9.0% execution time
J. Lin, K. Hamidouche, J. Zhang, X. Lu, A. Vishnu, D. Panda. Accelerating k-NN Algorithm with Hybrid MPI and OpenSHMEM,
OpenSHMEM 2015
• MaTEx: MPI-based Machine learning algorithm library
• k-NN: a popular supervised algorithm for classification
• Hybrid designs:
– Overlapped Data Flow; One-sided Data Transfer; Circular-buffer Structure

Outline

At Sender:
At Receiver:
MPI_Recv(r_devbuf, size, …);
inside
MVAPICH2
• Standard MPI interfaces used for unified data movement
• Takes advantage of Unified Virtual Addressing (>= CUDA 4.0)
• Overlaps data movement from GPU with RDMA transfers
High Performance and High Productivity
MPI_Send(s_devbuf, size, …);
GPU-Aware (CUDA-Aware) MPI Library: MVAPICH2-GPU

CUDA-Aware MPI: MVAPICH2-GDR 1.8-2.2 Releases
• Support for MPI communication from NVIDIA GPU device memory
• High performance RDMA-based inter-node point-to-point communication
(GPU-GPU, GPU-Host and Host-GPU)
• High performance intra-node point-to-point communication for multi-GPU
adapters/node (GPU-GPU, GPU-Host and Host-GPU)
• Taking advantage of CUDA IPC (available since CUDA 4.1) in intra-node
communication for multiple GPU adapters/node
• Optimized and tuned collectives for GPU device buffers
• MPI datatype support for point-to-point and collective communication from
GPU device buffers
• Unified memory

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MV2-GDR2.0b
MV2 w/o GDR
GPU-GPU Internode Bi-Bandwidth
Bi-Bandwidth(MB/s)
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MV2-GDR2.2 MV2-GDR2.0b
MV2 w/o GDR
GPU-GPU internode latency
Latency(us)
MVAPICH2-GDR-2.2
Intel Ivy Bridge (E5-2680 v2) node - 20 cores
NVIDIA Tesla K40c GPU
Mellanox Connect-X4 EDR HCA
CUDA 8.0
Mellanox OFED 3.0 with GPU-Direct-RDMA
10x
2X
11x
Performance of MVAPICH2-GPU with GPU-Direct RDMA (GDR)
2.18us
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MV2-GDR2.2
MV2-GDR2.0b
MV2 w/o GDR
GPU-GPU Internode Bandwidth
Bandwidth
(MB/s)
11X
2X
3X

• Platform: Wilkes (Intel Ivy Bridge + NVIDIA Tesla K20c + Mellanox Connect-IB)
• HoomdBlue Version 1.0.5
• GDRCOPY enabled: MV2_USE_CUDA=1 MV2_IBA_HCA=mlx5_0 MV2_IBA_EAGER_THRESHOLD=32768
MV2_VBUF_TOTAL_SIZE=32768 MV2_USE_GPUDIRECT_LOOPBACK_LIMIT=32768
MV2_USE_GPUDIRECT_GDRCOPY=1 MV2_USE_GPUDIRECT_GDRCOPY_LIMIT=16384
Application-Level Evaluation (HOOMD-blue)
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AverageTimeStepsper
second(TPS)
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MV2 MV2+GDR
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AverageTimeStepsper
second(TPS)
Number of Processes
64K Particles 256K Particles
2X
2X

Application-Level Evaluation (Cosmo) and Weather Forecasting in Switzerland
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1.2
16 32 64 96NormalizedExecutionTime
Number of GPUs
CSCS GPU cluster
Default Callback-based Event-based
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0.8
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1.2
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NormalizedExecutionTime
Number of GPUs
Wilkes GPU Cluster
Default Callback-based Event-based
• 2X improvement on 32 GPUs nodes
• 30% improvement on 96 GPU nodes (8 GPUs/node)
C. Chu, K. Hamidouche, A. Venkatesh, D. Banerjee , H. Subramoni, and D. K. Panda, Exploiting Maximal Overlap for Non-Contiguous Data
Movement Processing on Modern GPU-enabled Systems, IPDPS’16
On-going collaboration with CSCS and MeteoSwiss (Switzerland) in co-designing MV2-GDR and Cosmo Application
Cosmo model: http://www2.cosmo-model.org/content
/tasks/operational/meteoSwiss/

Need for Non-Uniform Memory Allocation in OpenSHMEM for
Heterogeneous Architectures
• MIC cores have limited
memory per core
• OpenSHMEM relies on
symmetric memory,
allocated using shmalloc()
• shmalloc() allocates same amount of memory on all PEs
• For applications running in symmetric mode, this limits the total heap size
• Similar issues for applications (even host-only) with memory load imbalance
(Graph500, Out-of-Core Sort, etc.)
• How to allocate different amounts of memory on host and MIC cores, and still be
able to communicate?
MIC MemoryHost Memory
Host Cores MIC Cores
Memory per core

OpenSHMEM Design for MIC Clusters
OpenSHMEM
Applications
Multi/Many-Core Architectures
with memory heterogeneity
MVAPICH2-X OpenSHMEM Runtime
InﬁniBand Networks
OpenSHMEM
Programming Model
InﬁniBand
Channel
SCIF Channel
Shared Memory/
CMA Channel
Proxy based Communication
Extensions
Application
Co-Design
Symmetric Memory Manager
• Non-Uniform Memory Allocation:
– Team-based Memory Allocation
(Proposed Extensions)
– Address Structure for non-uniform memory allocations
void shmem_team_create(shmem_team_t team, int *ranks,
int size, shmem_team_t *newteam);
void shmem_team_destroy(shmem_team_t *team);
void shmem_team_split(shmem_team_t team, int color,
int key, shmem_team_t *newteam);
int shmem_team_rank(shmem_team_t team);
int shmem_team_size(shmem_team_t team);
void *shmalloc_team (shmem_team_t team, size_t size);
void shfree_team(shmem_team_t team, void *addr);

HOST2
Proxy-based Designs for OpenSHMEM
OpenSHMEM Put using Active Proxy OpenSHMEM Get using Active Proxy
HOST1
MIC1
H
C
A
HOST2
MIC2
H
C
A
(1) IB REQ
(2) SCIF
Read
(2) IB
Write
(3) IB
FIN
HOST1
MIC1
H
C
A
MIC2
H
C
A
(3) IB
FIN
(2) SCIF
Read
(2) IB
Write
(1) IB
REQ
• Current generation architectures impose limitations on read bandwidth when HCA
reads from MIC memory
– Impacts both put and get operation performance
• Solution: Pipelined data transfer by proxy running on host using IB and SCIF channels
• Improves latency and bandwidth!

OpenSHMEM Put/Get Performance
OpenSHMEM Put Latency OpenSHMEM Get Latency
0
1000
2000
3000
4000
5000
1
4
16
64
256
1K
4K
16K
64K
256K
1M
4M
Latency(us)
Message Size
MV2X-Def
MV2X-Opt
0
1000
2000
3000
4000
5000
1
4
16
64
256
1K
4K
16K
64K
256K
1M
4M
Latency(us)
Message Size
MV2X-Def
MV2X-Opt
• Proxy-based designs alleviate hardware limitations
• Put Latency of 4M message: Default: 3911us, Optimized: 838us
• Get Latency of 4M message: Default: 3889us, Optimized: 837us
4.5X 4.6X

Performance Evaluations using Graph500
Native Mode (8 procs/MIC) Symmetric Mode (16 Host+16MIC)
• Graph500 Execution Time (Native Mode):
– 8 processes per MIC node
– At 512 processes , Default: 5.17s, Optimized: 4.96s
– Performance Improvement from MIC-aware collectives design
• Graph500 Execution Time (Symmetric Mode):
– 16 processes on each Host and MIC node
– At 1,024 processes, Default: 15.91s, Optimized: 12.41s
– Performance Improvement from MIC-aware collectives and proxy-based designs
0
2
4
6
64 128 256 512
ExecutionTime(s)
Number of Processes
MV2X-Def MV2X-Opt
0
5
10
15
20
25
128 256 512 1024
ExecutionTime(s)
Number of Processes
MV2X-Def MV2X-Opt
28%

Graph500 Evaluations with Extensions
• Redesigned Graph500 using MIC to overlap computation/communication
– Data Transfer to MIC memory; MIC cores pre-processes received data
– Host processes traverses vertices, and sends out new vertices
• Graph500 Execution time at 1,024 processes:
– 16 processes on each Host and MIC node
– Host-Only: .33s, Host+MIC with Extensions: .26s
• Magnitudes of improvement compared to default symmetric mode
– Default Symmetric Mode: 12.1s, Host+MIC Extensions: 0.16s
0
0.2
0.4
0.6
0.8
128 256 512 1024ExecutionTime(s)
Number of Processes
Host Host+MIC (extensions)
26%
J. Jose, K. Hamidouche, X. Lu, S. Potluri, J. Zhang, K. Tomko and D. K. Panda, High Performance OpenSHMEM for Intel MIC Clusters: Extensions,
Runtime Designs and Application Co-Design, IEEE International Conference on Cluster Computing (CLUSTER '14) (Best Paper Finalist)

• Architectures for Exascale systems are evolving
• Exascale systems will be constrained by
– Power
– Memory per core
– Data movement cost
– Faults
• Programming Models, Runtimes and Middleware need to be designed for
– Scalability
– Performance
– Fault-resilience
– Energy-awareness
– Programmability
– Productivity
• High Performance and Scalable MPI+X libraries are needed
• Highlighted some of the approaches taken by the MVAPICH2 project
• Need continuous innovation to have the right MPI+X libraries for Exascale
systems
Looking into the Future ….

Funding Acknowledgments
Funding Support by
Equipment Support by

Personnel Acknowledgments
Current Students
– A. Awan (Ph.D.)
– M. Bayatpour (Ph.D.)
– S. Chakraborthy (Ph.D.)
– C.-H. Chu (Ph.D.)
Past Students
– A. Augustine (M.S.)
– P. Balaji (Ph.D.)
– S. Bhagvat (M.S.)
– A. Bhat (M.S.)
– D. Buntinas (Ph.D.)
– L. Chai (Ph.D.)
– B. Chandrasekharan (M.S.)
– N. Dandapanthula (M.S.)
– V. Dhanraj (M.S.)
– T. Gangadharappa (M.S.)
– K. Gopalakrishnan (M.S.)
– R. Rajachandrasekar (Ph.D.)
– G. Santhanaraman (Ph.D.)
– A. Singh (Ph.D.)
– J. Sridhar (M.S.)
– S. Sur (Ph.D.)
– H. Subramoni (Ph.D.)
– K. Vaidyanathan (Ph.D.)
– A. Vishnu (Ph.D.)
– J. Wu (Ph.D.)
– W. Yu (Ph.D.)
Past Research Scientist
– S. Sur
Past Post-Docs
– D. Banerjee
– X. Besseron
– H.-W. Jin
– W. Huang (Ph.D.)
– W. Jiang (M.S.)
– J. Jose (Ph.D.)
– S. Kini (M.S.)
– M. Koop (Ph.D.)
– K. Kulkarni (M.S.)
– R. Kumar (M.S.)
– S. Krishnamoorthy (M.S.)
– K. Kandalla (Ph.D.)
– P. Lai (M.S.)
– J. Liu (Ph.D.)
– M. Luo (Ph.D.)
– A. Mamidala (Ph.D.)
– G. Marsh (M.S.)
– V. Meshram (M.S.)
– A. Moody (M.S.)
– S. Naravula (Ph.D.)
– R. Noronha (Ph.D.)
– X. Ouyang (Ph.D.)
– S. Pai (M.S.)
– S. Potluri (Ph.D.)
– S. Guganani (Ph.D.)
– J. Hashmi (Ph.D.)
– N. Islam (Ph.D.)
– M. Li (Ph.D.)
– J. Lin
– M. Luo
– E. Mancini
Current Research Scientists
– K. Hamidouche
– X. Lu
– H. Subramoni
Past Programmers
– D. Bureddy
– M. Arnold
– J. Perkins
Current Research Specialist
– J. Smith
– M. Rahman (Ph.D.)
– D. Shankar (Ph.D.)
– A. Venkatesh (Ph.D.)
– J. Zhang (Ph.D.)
– S. Marcarelli
– J. Vienne
– H. Wang

• Three Conference Tutorials (IB+HSE, IB+HSE Advanced, Big Data)
• HP-CAST
• Technical Papers (SC main conference; Doctoral Showcase; Poster; PDSW-
DISC, PAW, COMHPC, and ESPM2 Workshops)
• Booth Presentations (Mellanox, NVIDIA, NRL, PGAS)
• HPC Connection Workshop
• Will be stationed at Ohio Supercomputer Center/OH-TECH Booth (#1107)
– Multiple presentations and demos
• More Details from http://mvapich.cse.ohio-state.edu/talks/
OSU Team Will be Participating in Multiple Events at SC ‘16

panda@cse.ohio-state.edu, hamidouch@cse.ohio-state.edu
Thank You!
Network-Based Computing Laboratory
http://nowlab.cse.ohio-state.edu/
The MVAPICH Project
http://mvapich.cse.ohio-state.edu/

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