+============================== Standard 1 ==============================
+
+> *** Key Contributions: Please describe the key contributions of the
+ paper or lack thereof. Your comments should be specific and
+ justify your overall recommendation.
+
+This paper presents a new online frequency selecting algorithm for
+distributed iterative applications running on heterogeneous CPU nodes.
+Contrary to previous work (for homogeneous CPU), this heterogeneous
+context implies a vector of scaling factors and "slack times" before
+synchronizing the processes at each iteration. The models and the
+algorithm are clearly presented and detailed, and are validated on
+several benchmarks thanks to a simulator. Comparison with another
+scaling factor selection algorithm (which does not take into account
+communication times and heterogeneity) shows the relevance of this new
+algorithm which manages to significantly reduce the energy consumption
+with acceptable performance overhead.
+
+Overall, this is a very solid work, and the paper is well-written and
+very clear.
+
+The main flaw of this paper is that the evaluation is only done via a
+simulator. As mentioned in future work, evaluations on real
+heterogeneous CPU platforms (with real power measurements) will be
+necessary (as future work) to validate definitely this algorithm and
+the models.
+
+> *** Suggestions for Improvement: Additional comments and suggestions
+ for improvement in the technical content or the presentation.
+ Please be as detailed and constructive as you can be.
+
+The energy and performance models rely on compute-bound programs,
+where the computation time is linearly proportional to the processor
+frequency. Does this apply to all NAS benchmarks ? The authors should
+specify which NAS benchmarks are memory-bound (if any), and how their
+model apply to these memory-bound benchmarks.
+
+Moreover, in section III it seems that the authors assume that the
+communication time (without slack time) is the same for all processors
+provided they have the same communication volume. This could be
+pointed out more clearly in the paper. Also, does this apply to all
+NAS benchmarks? Does it also depends on the placement of the MPI
+processes? I assume that for the same communication volume, the
+communication time will differ whether the processes are on
+neighbouring nodes or are on distant nodes (especially with 128 or 144
+nodes).
+Could the authors discuss in the text?
+
+The authors consider that the communication time only apply to static
+power, which means that no CPU cycle is used for the MPI
+communications. Does this implies specific networks (like Infiniband)
+with RDMA?
+This could be clarified in the paper.
+
+Finally, the algorithm applies to synchronous iterative applications:
+is this the case for all NAS benchmarks evaluated in this paper? This
+could also be specified in the paper.
+
+Figures 2a and 2b : I do not understand why the energy curve in Fig.2b
+does not have the same shape as the one in Fig.2a.
+Could the authors specify this in the text?
+
+Minor comments :
+- The authors could specify in the abstract that "heterogeneous
+ platforms" refer to heterogeneous CPUs (not to CPU-GPU nodes).
+- The terms "in the same direction" (used twice in section IV) are
+ unclear and should be rewritten.
+- Section V.A : replace "because selecting frequency scaling factors
+ higher than the higher bound" by "because selecting frequencies
+ higher than the higher bound"?
+
+> *** Significance: Assess the significance of the topic addressed in
+ the paper.
+
+Excellent (5)
+
+> *** Originality/Novelty (of contribution): How novel are the
+ concepts presented in the paper?
+
+Above average (4)
+
+> *** Technical Soundness: How strong are the techniques and
+ methodologies used in the paper?
+
+Excellent (5)
+
+> *** Overall Recommendation: Your final rating should be consistent
+ with your ratings on previous questions.
+
+Accept (5)
+
+============================== Standard 2 ==============================
+
+> *** Key Contributions: Please describe the key contributions of the
+ paper or lack thereof. Your comments should be specific and
+ justify your overall recommendation.
+
+The paper proposed a frequency selection algorithm for heterogeneous
+platforms. The algorithm proposed the maximum distance between the
+energy consumption and the performance to get the trade off scale
+factor. on This is an interesting paper with good trial to cover many
+factors.
+
+The paper ran NPB benchmarks to verify the algorithm but there is no
+comparison between the results at the the trade-off scale factor and
+those from all other possible scale factors without applying the
+algorithm. Without this, it is not reliable to validate the algorithm.
+
+> *** Suggestions for Improvement: Additional comments and suggestions
+ for improvement in the technical content or the presentation.
+ Please be as detailed and constructive as you can be.
+
+There are too much tables i.e. II-VII in section VI. Better to
+summarize them in a couple of figures.
+
+It is necessary to describe the overhead of the algorithm which is
+missed in the paper.
+
+> *** Significance: Assess the significance of the topic addressed in
+ the paper.
+
+Average (3)
+
+> *** Originality/Novelty (of contribution): How novel are the
+ concepts presented in the paper?
+
+Average (3)
+
+> *** Technical Soundness: How strong are the techniques and
+ methodologies used in the paper?
+
+Acceptable (3)
+
+> *** Overall Recommendation: Your final rating should be consistent
+ with your ratings on previous questions.
+
+Weak Accept (4)
+
+============================== Standard 3 ==============================
+
+> *** Key Contributions: Please describe the key contributions of the
+ paper or lack thereof. Your comments should be specific and
+ justify your overall recommendation.
+
+The paper develops DVFS performance models and an online algorithm to
+optimize time and energy for iterative message passing applications on
+a heterogeneous CPU cluster. An objective function is developed to
+express the time energy tradeoff. Results using a simulated framework
+show worthwhile energy gains for acceptable loss of execution time. A
+comparison with a more general pre-existing algorithm show modest
+improvements in energy and and energy-time tradeoff.
+
+The paper is well-written and is technically sound. Its significance
+is slightly diminished due to the fact that previous work has largely
+dealt with this issue on scenarios that are of stronger interests
+and/or are less specialized.
+
+> *** Suggestions for Improvement: Additional comments and suggestions
+ for improvement in the technical content or the presentation.
+ Please be as detailed and constructive as you can be.
+
+The abstract would be sharpened it it contained numbers relating to
+the performance degradation and comparison.
+
+III.A. The modelling of the communication time being independent of
+the frequency is questionable, even if it is backed up by a 10year old
+reference. While slack time is not affected, my own research has shown
+that communication bandwidth does clearly increase with frequency,
+albeit in a sub-linear fashion. The use of taking the minimum for
+communication time (3) needs better explanation, as it is
+counter-intuitive.
+
+I would like to some explanation as to why it takes so many iterations
+for the algorithm to select the best vector, and whether this can be
+improved. While the NAS benchmarks have a standard number of
+iterations, it would be helpful to the reader to indicate what these
+are in VI.
+
+The results on a real heterogeneous platform in the future work will
+be interesting.
+
+There are a number of small grammatical errors:
+
+p2. ``to satisfy some objectives while taking into account all the
+constraints,'': a comma is needed before `while' to match the 2nd
+
+Fig2(b) normalize -> normalized
+
+p4 ``following the same direction'': use `follow'
+
+Alg1: F_diff_i: difference -> differences
+
+p6: on all left frequencies -> on all remaining frequencies
+
+while it lowers the frequency of all other nodes ->
+while it lowers the frequencies of all other nodes
+
+``the proposed algorithm is not an exact method it does'':
+put a : before it
+
+p8: on different number of nodes -> on different numbers of nodes
+the GC benchmark significantly decrease ->
+the CG benchmark significantly decreases
+
+> *** Significance: Assess the significance of the topic addressed in
+ the paper.
+
+Above average (4)
+
+> *** Originality/Novelty (of contribution): How novel are the
+ concepts presented in the paper?
+
+Above average (4)
+
+> *** Technical Soundness: How strong are the techniques and
+ methodologies used in the paper?
+
+Excellent (5)
+
+> *** Overall Recommendation: Your final rating should be consistent
+ with your ratings on previous questions.
+
+Strong Accept (6)
+
+============================== Standard 4 ==============================
+
+> *** Key Contributions: Please describe the key contributions of the
+ paper or lack thereof. Your comments should be specific and
+ justify your overall recommendation.
+
+In this paper, a new online frequency selecting algorithm for
+heterogeneous platforms is presented. It selects the frequencies and
+tries to give the best trade-off between energy saving and performance
+degradation, for each node computing the message passing iterative
+application. The algorithm has a small overhead and works without
+training or profiling. It uses a new energy model for message passing
+iterative applications running on a het- erogeneous platform. The
+proposed algorithm is evaluated on the SimGrid simulator while running
+the NAS parallel benchmarks. The experiments show that it reduces the
+energy consumption by up to 35 % while limiting the performance
+degradation as much as possible. Finally, the algorithm is compared to
+an existing method, the comparison results showing that it outperforms
+the latter.
+
+> *** Suggestions for Improvement: Additional comments and suggestions
+ for improvement in the technical content or the presentation.
+ Please be as detailed and constructive as you can be.
+
+I did not see every clearly that if the proposed online algorithm can
+achieve the optimal selection. If only the heustrics, then how close
+to the optimal? I would like to see more theoretical or experimental
+results if possible since the authors claims the "the best trade-off
+between energy saving and performance degradation".
+
+> *** Significance: Assess the significance of the topic addressed in
+ the paper.
+
+Excellent (5)
+
+> *** Originality/Novelty (of contribution): How novel are the
+ concepts presented in the paper?
+
+Excellent (5)
+
+> *** Technical Soundness: How strong are the techniques and
+ methodologies used in the paper?
+
+Strong (4)
+
+> *** Overall Recommendation: Your final rating should be consistent
+ with your ratings on previous questions.
+
+Strong Accept (6)
+
+============================== Standard 5 ==============================
+
+> *** Key Contributions: Please describe the key contributions of the
+ paper or lack thereof. Your comments should be specific and
+ justify your overall recommendation.
+
+The paper considers the DVFS technique and presents an energy model
+for DVFS systems that also takes the communication time into
+consideration. An new algorithm for selecting the scaling factors is
+presented. The algorithm uses a vector of scaling factors, one for
+each node, and determines the scaling factors such that best trade-off
+between minimizing the energy consumption and maximizing the
+performance for a synchronous iterative algorithm is reached. The
+algorithm works during execution time and uses the first interation
+step for collecting the information required for the scaling factor
+selection. An experimental evaluation is given using the SimGrid
+environment.
+
+The paper is well written and structured and should be accepted. It
+is solid work and provides new contributions by extending earlier
+energy models with communication time concerns and proposes a new
+algorithm for DVFS control.
+
+> *** Suggestions for Improvement: Additional comments and suggestions
+ for improvement in the technical content or the presentation.
+ Please be as detailed and constructive as you can be.
+
+Algorithm 1 in Section V could be explained in more detail. As far as
+I can see, it tests all possible frequencies or scaling factors for
+the different nodes and selects the best as indicated by the model. I
+was wondering whether all combinations of scaling factors are tested
+or whether this is not necessary because of the behavior of the
+communication.
+The accuracy of the frequency selection depends on the accuracy of the
+model used for the computation of the scaling factors. It would be
+interesting to see how accurate the model is for real systems.
+However, I see that this might be difficult to capture in practice.
+
+> *** Significance: Assess the significance of the topic addressed in
+ the paper.
+
+Excellent (5)
+
+> *** Originality/Novelty (of contribution): How novel are the
+ concepts presented in the paper?
+
+Above average (4)
+
+> *** Technical Soundness: How strong are the techniques and
+ methodologies used in the paper?
+
+Excellent (5)
+
+> *** Overall Recommendation: Your final rating should be consistent
+ with your ratings on previous questions.
+
+Accept (5)
