LiMIC2: Linux kernel module for MPI Intra-node Communication


[Table of Contents]
1. Introduction
2. References
3. Installation
4. Contact


[1. Introduction]

LiMIC is the Linux kernel module developed by System Software Laboratory 
(SSLab) of Konkuk University. It enables high-performance MPI intra-node 
communication over multi-core systems. LiMIC achieves very good 
performance since it no longer requires MPI libraries to copy messages 
in and out of shared memory regions for intra-node communication. Rather, 
LiMIC enables messages to be copied directly from sending process' 
memory to the receiver process. Thus, LiMIC eliminates unnecessary 
message copies and enhances cache utilization. LiMIC has two different 
designs called LiMIC1(LiMIC 1st Generation) and LiMIC2(LiMIC 2nd 
Generation). 

LiMIC1 is a stand-alone communication module with generalized 
kernel-access interfaces. The module manages send, receive, and 
completion queues internally so that, once the MPI library decides to 
use intra-node communication channel, simply calls the interface and 
let the communication module handle the message transportation between 
intra-node processes. However, having the separate message queues from 
the MPI library brings on many tricky issues, which may result in low 
scalability in many-core systems.

To overcome the limitations of LiMIC1, LiMIC2 provides lightweight 
primitives to perform the memory mapping between different processes. 
The kernel module exposes the interface for memory mapping and data 
copy to the MPI library. The lightweight primitives do not need to have 
any internal queues and data structures shared between intra-node 
processes. Therefore, the lightweight primitives can avoid the 
synchronization and MPI message matching, which can result in lower 
overhead and increase the parallelism of local MPI processes. LiMIC2 
has the potential of achieving better performance than LiMIC1.
LiMIC2 consists of a runtime loadable kernel module and user library. 
The kernel module implements the kernel-level memory mapping between 
different processes without any kernel modification. The user library 
provides the interface to the kernel module functions for the MPI library.
Currently only LiMIC2 is supported and distributed from SSLab homepage,
http://sslab.konkuk.ac.kr, under BSD license.

LiMIC2 has been adopted into MVAPICH/MVAPICH2 developed by Network-Based 
Computing Laboratory (NBCL) of the Ohio State University. MVAPICH/MVAPICH2 
is the open-source implementation of MPI/MPI2 library for InfiniBand and 
iWARP clusters. This sofware is being used by more than 800 organizations 
world-wide. You can download the software at the MVAPICH website (http://
mvapich.cse.ohio-state.edu).


[2. References]

H.-W. Jin, S. Sur, L. Chai, and D. K. Panda, "Lightweight Kernel-Level 
Primitives for High-Performance MPI Intra-Node Communication over 
Multi-Core Systems," In Proc. of IEEE Cluster 2007, pp. 446-451, 
September 2007.

L. Chai, D. Nagaraj, P. Lai, H.-W. Jin, and D. K. Panda, "Designing An 
Efficient Kernel-level and User-level Hybrid Approach for MPI Intra-node 
Communication on Multi-core Systems," In Proc. of ICPP-08, pp. 222-229, 
September 2008.

H.-W. Jin, S. Sur, L. Chai, and D. K. Panda, "LiMIC: Support for 
High-Performance MPI Intra-Node Communication on Linux Cluster," In Proc. 
of ICPP-05, pp. 184-191, June 2005.

L. Chai, S. Sur, H.-W. Jin, and D. K. Panda, "Analysis of Design 
Considerations for Optimizing Multi-Channel MPI over InfiniBand," In Proc. 
of CAC 2005, April 2005.


[3. Installation]

3.1 Software Download
	http://sslab.konkuk.ac.kr for LiMIC2 only
	http://mvapich.cse.ohio-state.edu for MVAPICH2+LiMIC2 package

3.2 Compiling LiMIC2 Library + Kernel Module
	./configure --enable-module --prefix=/usr --sysconfdir=/etc
	make 

3.3 Installation
	make install

3.4 Uninstall
	make uninstall

3.5 Package specific options
  --enable-module         Build Limic2 kernel module.
  --with-kernel=RELEASE   Specify kernel release to use for building LiMIC2
                          kernel module. Defaults to currently running kernel.
  --with-kernel-mod=DIR   Path to install LiMIC2 kernel module. Defaults to
                          external module location for the kernel the module
                          is built against.


[4. Contact]

Hyun-Wook (Jin) Jin
Department of Computer Science & Engineering
Konkuk University
1, Hwayang-dong, Kwangjin-ku
Seoul 143-701, Korea
jinh@konkuk.ac.kr
home.konkuk.ac.kr/~jinh
