Update solvers to run CPU backend

Author: utkarsh530

benchmarks/CPU_vs_GPU/benchmark.jl

@@ -3,7 +3,7 @@ using CUDA
 
 device!(2)
 
-N = 10
+N = 3
 function rosenbrock(x, p)
     sum(p[2] * (x[i + 1] - x[i]^2)^2 + (p[1] - x[i])^2 for i in 1:(length(x) - 1))
 end

src/kernels.jl

@@ -48,19 +48,18 @@ end
     particle = @private SPSOParticle{T1, T2} 1
 
     @inbounds particle[1] = gpu_particles[i]
-    @inbounds gbest = gbest_ref[1]
-
     # Initialize cost to be Inf
     if tidx == 1
-        fill!(best_queue, SPSOGBest(gbest.position, convert(typeof(gbest.cost), Inf)))
+        fill!(best_queue,
+            SPSOGBest(particle[1].position, convert(typeof(particle[1].cost), Inf)))
         queue_num[1] = UInt32(0)
     end
 
     @synchronize
 
     @inbounds particle[1] = update_particle_state(particle[1],
         prob,
-        gbest,
+        gbest_ref[1],
         w,
         c1,
         c2,
@@ -69,8 +68,7 @@ end
 
     @synchronize
 
-    gbest = @inbounds gbest_ref[1]
-    if particle[1].best_cost < gbest.cost
+    @inbounds if particle[1].best_cost < gbest_ref[1].cost
         queue_idx = @atomic queue_num[1] += UInt32(1)
         @inbounds best_queue[queue_idx] = SPSOGBest(particle[1].best_position,
             particle[1].best_cost)
@@ -96,8 +94,7 @@ end
             end
 
             # Update global best fit
-            gbest = @inbounds gbest_ref[1]
-            @inbounds if best_queue[1].cost < gbest.cost
+            @inbounds if best_queue[1].cost < gbest_ref[1].cost
                 gbest_ref[1] = best_queue[1]
             end
 
@@ -153,6 +150,18 @@ end
     @inbounds gpu_particles[i] = particle
 end
 
+@kernel function update_particle_states!(prob, gpu_particles, gbest, w,
+        opt::ParallelSyncPSOKernel{Backend, T, G, H}; c1 = 1.4962f0,
+        c2 = 1.4962f0) where {Backend <: CPU, T, G, H}
+    i = @index(Global, Linear)
+
+    @inbounds particle = gpu_particles[i]
+
+    particle = update_particle_state(particle, prob, gbest, w, c1, c2, i, opt)
+
+    @inbounds gpu_particles[i] = particle
+end
+
 @kernel function update_particle_states_async!(prob,
         gpu_particles,
         gbest_ref,

src/lowerlevel_solve.jl

@@ -28,6 +28,31 @@ function vectorized_solve!(prob,
     return gbest, gpu_particles
 end
 
+function vectorized_solve!(prob,
+        gbest,
+        gpu_particles, opt::ParallelSyncPSOKernel{Backend, T, G, H};
+        maxiters = 100,
+        w = 0.7298f0,
+        wdamp = 1.0f0,
+        debug = false) where {Backend <: CPU, T, G, H}
+    backend = get_backend(gpu_particles)
+
+    update_particle_kernel = update_particle_states!(backend)
+
+    for i in 1:maxiters
+        update_particle_kernel(prob,
+            gpu_particles,
+            gbest,
+            w, opt;
+            ndrange = length(gpu_particles))
+        best_particle = minimum(gpu_particles)
+        gbest = SPSOGBest(best_particle.position, best_particle.best_cost)
+        w = w * wdamp
+    end
+
+    return gbest, gpu_particles
+end
+
 function vectorized_solve!(prob,
         gbest,
         gpu_particles, opt::ParallelPSOKernel, ::Val{true};