From: Arnaud Giersch Date: Thu, 26 Jun 2014 14:20:27 +0000 (+0200) Subject: Add hpcc reviews. X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/hpcc2014.git/commitdiff_plain/2ab7edb17f96029ed0ab0be725adb249a5b11818?ds=inline Add hpcc reviews. --- diff --git a/hpcc2014_reviews.txt b/hpcc2014_reviews.txt new file mode 100644 index 0000000..7d07a3d --- /dev/null +++ b/hpcc2014_reviews.txt @@ -0,0 +1,199 @@ +De: HPCC 2014 +Objet: HPCC 2014 notification for paper 121 +Date: 26 juin 2014 15:24:40 UTC+2 +À: David Laiymani + +Dear David Laiymani, + +On behalf of the Program Committee of HPCC 2014, we would like to +inform you that the paper titled:Simulation of Asynchronous Iterative +Algorithms Using SimGrid(paper ID number 121) has not been accepted +for presentation at the main track of the conference but due to its +quality, your paper is accepted in the associated Workshops of the +HPCC2014 conference, and will be published in the same proceedings by +IEEE CPS and indexed in IEEE Xplorer. + +Please modify your paper according to the instructions and comments +provided by the reviewers. + +Please prepare and submit your final camera ready paper and follow all +STEPs to ensure the submission process is completed +successfully. Please note Camera ready submission deadline is 15 July +2014. + +Authors must follow the IEEE formatting instruction. + +For further information please check: + +www.computational-science.org/HPCC2014 + +We are looking forward to meeting you at the HPCC 2014 conference. + +S. Khaddaj, Program Chair of HPCC 2014 +J. Bourgeois, General Chair of HPCC2014 +F. Magoules, General Chair of HPCC2014 + + +----------------------- REVIEW 1 --------------------- +PAPER: 121 +TITLE: Simulation of Asynchronous Iterative Algorithms Using SimGrid +AUTHORS: Charles Emile Ramamonjisoa, David Laiymani, Arnaud Giersch, + Lilia Ziane Khodja and Raphaël Couturier + + +----------- REVIEW ----------- +The contribution of the paper could be better described. + +The authors state that: + +"we show that SimGrid is an efficient simulation +tool that has enabled .." + +If this is one of the goals of the paper to present the +capabilities/strength of SimGrid, then they should compare it with +other tools for the comparison of the two methods. + +Regarding the comparison of the two methods, the possible scalability +expected in the case of larger platforms might also be commended / +discussed. + + +----------------------- REVIEW 2 --------------------- +PAPER: 121 +TITLE: Simulation of Asynchronous Iterative Algorithms Using SimGrid +AUTHORS: Charles Emile Ramamonjisoa, David Laiymani, Arnaud Giersch, + Lilia Ziane Khodja and Raphaël Couturier + + +----------- REVIEW ----------- +This paper describes the simulation of an adapted (authors say +slightly changed) GMRES solver on the SimGrid simulation framework; +the GMRES solver is changed from synchronous iterative solution to a +asynchronous iteration scheme in order to overcome latencies when +interconnecting computers in a Grid environment. + +The prejudice of the paper is that the GMRES algorithm is not using +non-blocking communication to begin with. + + +You mention that for running with SimGrid using SMPI, "little" or no +modification need to be done to the original code: what kind of +modifications are necessary -- and did You have to apply any +modification to run with SMPI? (in a later section of the paper, +changing / deleting global variables were mentioned -- due to the +threaded execution of simulated MPI processes...) + + +SimGrid uses a "fluid model" -- what does that mean? + +The local convergence criterion (k<=MaxIter) seams wrong and should +rather read: k == MaxIter? + +As far as the reviewer can tell, SMPI removes heavy computation by +making assumptions on the CPU performance of the simulated code -- +which however is not true with most Grid environments where You do +have mixed architectures and mixed performance characteristics. How +is this handled? + +However, the main gripe about this paper is the rather unrealistic +assumption on bandwidth (5 Mbps!) and latency (20ms): the internal +network of a cluster may be Infiniband, with bw of Gigabytes/sec and +micro-second latency, while a second cluster may be reachable over +Gigabit-Ethernet with 100-200x the latency... This would be a setup, +where a (even slight) gain would provide more convincing results. + + + +Some knitpicks include: +- Abstract: "Behaviours", please no plural +- Sec II (and others): "As exposed" --> "As described" +- Sec II: "And important idle times" --> better "useless idle times + used for synchronization" +- Sec III: "by the mean of an XML file" --> "by means of an XML file". +- SEC IV.B: did not encouter ... unless some code debugging" --> + please rewrite the unless part... +- SEC V: "Hosts processors power" --> "Host processor power" + + +----------------------- REVIEW 3 --------------------- +PAPER: 121 +TITLE: Simulation of Asynchronous Iterative Algorithms Using SimGrid +AUTHORS: Charles Emile Ramamonjisoa, David Laiymani, Arnaud Giersch, + Lilia Ziane Khodja and Raphaël Couturier + + +----------- REVIEW ----------- +The submitted paper purports to be the first simulation of +asynchronous iterative algorithms and predicts that, for a particular +cluster configurations with very high latency (20ms) and very low +bandwidths (5/50 Mbit/s), an unpreconditioned asynchronous +multisplitting algorithm will be faster than an unpreconditioned GMRES +algorithm for solving a 3D Poisson equation. + +Several issues with respect to the relevance of these results deserve +discussion: + +1) There is no substantial discussion of the fundamental additions to +SimGrid that were required in order to support the simulation of +asynchronous iterative algorithms. If no extensions were required, +then I am unsure as to how this aspect of the work is a contribution. + +2) The model problem of a 3D Poisson equation with no preconditioner +is regrettable due to the large number of fast solvers available that +have been available for many decades. For this reason, as is, the +results are not relevant to the solution of PDEs. However, a similar +computational structure appears within the context of gradient descent +methods for the solution of convex optimization problems, and +asynchronous algorithms are quite common. I would humbly suggest such +a model problem in the future unless either a more challenging PDE is +tackled or a non-trivial preconditioner is incorporated. + +3) This is somewhat of a minor point, but I did not see an explicit +discussion of the link between a global relative residual norm, +|| A x - b|| / || b ||, and the local convergence criterion used in +the asynchronous algorithm, which tested for the infinity norm of the +local computation. When "precision" is reported in Table I, is it +referring to a consistent global convergence criterion? And, if so, +what is it precisely referring to? + +4) Typical latencies within clusters are on the order of a +microsecond, and the latency used to produce Table I is more than +three orders of magnitude higher (20ms). It would be helpful if more +justification was given for why such a high latency is +relevant. Furthermore, the chosen bandwidths (5 Mbit/s and 50 Mbit/s) +are closer to a non-commercial home internet connection than a +commercial ethernet connection. + +Overall, I feel that a significant number of issues should be +addressed before publication would be warranted. + + +----------------------- REVIEW 4 --------------------- +PAPER: 121 +TITLE: Simulation of Asynchronous Iterative Algorithms Using SimGrid +AUTHORS: Charles Emile Ramamonjisoa, David Laiymani, Arnaud Giersch, + Lilia Ziane Khodja and Raphaël Couturier + + +----------- REVIEW ----------- +This is a very interesting paper devoted to the implementation in a +grid environment of some asynchronous algorithm. These algorithms are +indeed very powerfull, and the more latency, the more efficient are +these algorithms. A comparison of a synchronous GMRES and an +asynchronous multi-splitting is presented. The obtained results are +interesting and confirm the efficiency of these methods. + + +----------------------- REVIEW 5 --------------------- +PAPER: 121 +TITLE: Simulation of Asynchronous Iterative Algorithms Using SimGrid +AUTHORS: Charles Emile Ramamonjisoa, David Laiymani, Arnaud Giersch, + Lilia Ziane Khodja and Raphaël Couturier + + +----------- REVIEW ----------- +This paper is a mix between a short and a long paper, it presents +preliminary works on simulation of asynchronous iterative algorithms +using SimGrid. I recommend to accept it as a short paper. + +