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DTSTAMP:20260605T154541Z
LOCATION:Plenary Room (Bldg. 6 - 001)
DTSTART;TZID=Europe/Stockholm:20260629T192000
DTEND;TZID=Europe/Stockholm:20260629T192100
UID:submissions.pasc-conference.org_PASC26_sess124_pos117@linklings.com
SUMMARY:P01 - Accelerating Lattice QCD Dirac GCR Solvers with Multiple Rig
 ht-Hand Sides (MRHS)
DESCRIPTION:JingJing Li and Roman Gruber (University of Bern) and Marina K
 rstic Marinkovic (ETH Zurich)\n\nLattice QCD simulations are often limited
  by the memory-bandwidth bottlenecks of solving the Dirac equation for num
 erous source vectors. We present an optimised Multiple Right-Hand Side (MR
 HS) Generalised Conjugate Residual (GCR) solver in the openQxD framework t
 hat addresses these limitations. By transitioning the core computational k
 ernel from Matrix-Vector to Matrix-Matrix multiplication, we significantly
  increase arithmetic intensity and improve cache locality. Additionally, w
 e reduce communication overhead in distributed-memory systems by bundling 
 MPI boundary exchanges, effectively lowering communication latency from O(
 number of RHS) to O(1). Our MRHS implementation offers a four-fold perform
 ance increase for Dirac operator applications on modern HPC architectures.
  \n\nThe MRHS implementation in established codebase QUDA is also examined
 . QUDA’s GPU implementation of MRHS improves GPU saturation and increases 
 energy efficiency, reducing the energy cost per solve by a factor of 1.6. 
 This provides a scalable and efficient solution for high-throughput lattic
 e simulations requiring multiple solves of the same Dirac equation.\n\nSes
 sion Chair: Miroslava Nedyalkova (University of Fribourg)\n\n
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