Ray, The CSAC pages is fixed now and should be updated daily. 150k was granted to the Lattice-QCD project as well. - JB On Thu, Dec 10, 2015 at 6:11 PM, Bair, Raymond A. <[email protected]> wrote:

OK for 150K.

BTW, the CASC web report shows a date of 12/4.

On 12/10/15, 12:12 PM, "[email protected] on behalf of John Blaas" <[email protected] on behalf of [email protected]> wrote:

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Any arguments for not granting this allocation?

- JB

On Fri, Dec 4, 2015 at 9:44 AM, Bair, Raymond A. <[email protected]> wrote:

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The CSAC report shows a balance of 186K. Is it out of date?

https://www.lcrc.anl.gov/jazz/CSAC/project-reports-2016/Summary/summary-d et ails-name-ascending.php?sortOrder=ascending&reportName=name

Ray

On 12/3/15, 3:48 PM, "[email protected] on behalf of [email protected]" <[email protected] on behalf of [email protected]> wrote:

...

Hello,

A change in allocation has been requested:

Requester: sinclair (Donald Sinclair) Project: Lattice-QCD Title: Lattice simulations of Conformal and Walking Technicolor. Description: We perform simulations to evaluate the functional integrals of QCD-like theories formulated on a discrete space-time lattice, to enable determination of the non-perturbative aspects these theories. These include the properties of these theories at non-zero temperature, including the scales of confinement and chiral symmetry breaking, and such zero temperature properties as spectra (including the Higgs mass), decay constants and the running of the gauge coupling constant. We are particularly interested in those theories where the coupling constant evolves very slowly, since these are candidate 'Walking- Technicolor' theories. Related to these are theories with an infrared fixed point (conformal field theories). Our first goal is to differentiate between these two different types of behaviour for candidate theories.

We are performing simulations of QCD-like theories which are models for Walking or Conformal Technicolor. We have been studying theories which are essentially QCD but with colour-sextet rather than colour-triplet quarks. We hope to measure the running of the QCD coupling constant. For 2 or 3 flavours, 2-loop perturbation theory predicts an infrared fixed point.

For 2 flavours, it is possible that a chiral condensate forms before this fixed point is reached. If so, the fixed point is avoided, the theory is confining, and chiral symmetry breaks spontaneously. However, there is a region where the coupling constant evolves very slowly. These are the properties required for a walking technicolor theory. Simulations we have performed so far at finite temperature suggest that this theory might be conformal. So far, however, the results are inconclusive.

For 3 flavours we know that the theory should be conformal. Simulations at N_t=6 (12^3 X 6 lattice) and N_t=8 (12^3 X 8 lattice), some of which used Fusion, did not yet show evidence of conformality. We are now simulating at N_t=12 (24^3 X 12 lattice). We started these simulations on Blues, and intend to continue them in FY2016 on Blues to enable continuity during the period when Edison at NERSC is unavailable due to a site move.

Our sextet quark codes are based on our earlier triplet quark codes and use the RHMC simulation method. The Rational Hybrid Monte Carlo (RHMC) is a stochastic molecular dynamics algorithm. The functional integral of QCD is written as a partition function of a classical field theory evolving in a fictitious time. The determinant of the Dirac operator raised to a fractional power is calculated by introducing bosonic fields (pseudofermions), and sandwiching this Dirac operator raised to minus said fractional power between them. This fractional power of the Dirac operator is approximated to machine accuracy by a rational approximation. After defining this theory on a discrete space-time lattice, the inversions required by the partial-fraction expansion of the rational approximation are performed using Krylov space methods, in particular a multi-shift extension of the conjugate gradient algorithm. A global Metropolis Monte-Carlo accept/reject step applied at the end of each trajectory removes discretization errors introduced by the numerical integration of these stochastic equations of motion. We parallelize the code by assigning a fixed number of adjacent lattice sites to each MPI task. Network bandwidth ultimately limits how small a chunk of the lattice can be assigned to each task.

Our 24^3 X 12 runs will be performed on 288 cores (18 nodes) of Blues.

A short benchmark run of the 24^3 X 12 codes yielded 667 Gflops or 2.3 Gflops/core. Since we have seen performances of > 3 Gflops/core on machines with similar processors, and > 4 Gflops/node on Edison, we suspect that at least 3 Gflops/core should be achievable on this machine. Since we have nearly exhausted our allocation on Blues, we cannot perform more extensive tests. Scaling tests on Fusion and on Edison at NERSC for numbers of cores from 24 up to 288 cores indicate that the per core performance increases up to 288 cores, which we believe to be related to cache usage.

Our new project simulating QCD at finite mu using Complex Langevin with Gauge Cooling is currently running as serial code on several platforms, including Blues, where the little allocation we have remaining does not allow us to run anything else. The Langevin equation method is essentially the limiting case of the above algorithm in its older form (without the rational approximation), when each trajectory involves a single update of the fields. Its extension to the complex manifold merely involves extending the gauge-field manifold from SU(3) to SL(3,C). The main reason that it is serial code is that this project is still in its exploratory phase, meaning that modifications of the algorithm are still possible. Converting to parallel MPI code will not be difficult, since the compute-intensive kernel is almost identical to that of our older QCD codes, as are many other parts of the code. We do, however, expect some performance degradation, since we have been running this code at 64-bit precision, rather than the 32-bit precision of our QCD codes. When we have converted to parallel code, we will cease our serial runs on Blues. While we perform zero-temperature simulations at NERSC, TACC and SDSC, we plan to start finite temperature simulations on Blues, probably starting on 8^3*4 lattices using 16 or 32 cores, and then moving to 12^3*4 and 12^3*6 lattices on 48 and 72 cores respectively. Note that these runs with low-level parallelism are discouraged on the flagship machines at NERSC.

Our requested allocation is based on running 2 288-core jobs half of the time for the first 4-months and jobs using a total of 144 cores half the time for the last 8 months. Expected percentage of allocation for serial jobs -- 5%. Current: undetermined amount Justification: We have not yet performed a detailed scaling analysis on Blues, however, we have such analyses performed on Fusion as well as Edison at NERSC. For Fusion, for our QCD with sextet quarks code on a 24^3 X 12 lattice running on Fusion we observed the following performances: 24 cores = 45 Gflops = 1.9 Gflops/core 48 cores = 95 Gflops = 2.0 Gflops/core 72 cores = 148 Gflops = 2.1 Gflops/core 96 cores = 220 Gflops = 2.3 Gflops/core 144 cores = 369 Gflops = 2.6 Gflops/core 288 cores = 784 Gflops = 2.7 Gflops/core For the same code and lattice size running on Edison at NERSC we observed the following performances. 24 cores = 62 Gflops = 2.6 Gflops/core 48 cores = 129 Gflops = 2.7 Gflops/core 72 cores = 214 Gflops = 3.0 Gflops/core 96 cores = 330 Gflops = 3.4 Gflops/core 144 cores = 561 Gflops = 3.9 Gflops/core 288 cores = 1219 Gflops = 4.2 Gflops/core We use a custom assignment of tasks to nodes in order to minimize communications. Earlier recoding reduced the number of global reductions in the routines, which use most of the CPU time, by a factor of 2.

The new Complex Langevin codes are still serial, but they will be parallelized in the same manner as the RHMC codes. Algorithm changes are under consideration. There is also the possibility that we will prepare an OpenMP version in preparation for running on Cori II at NERSC.

Requested: 150000

A specific reason has been given: Needed to finish current runs. Other resources are not available. Allocation on Stampede at TACC is exhausted. Allocation on Comet at SDSC is almost exhausted. NERSC is severely impacted by site move -- Edison is offline for 6 weeks, Hopper will be decommissioned 15th December, and Cori I is inadequate to take up the slack.

This needs to be approved and the final allocation amount decided upon.

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