apu/vp: Make number of voice workers dynamic

Adds a new config option to control number of workers. If the value of
the option is 0 (default), then the logical CPU count, as reported by
SDL, is used.

Author: mborgerson

config_spec.yml

@@ -214,6 +214,10 @@ display:
         default: false
 
 audio:
+  vp:
+    num_workers:
+      type: integer
+      default: 0  # 0 = auto
   use_dsp: bool
   hrtf:
     type: bool

hw/xbox/mcpx/apu/apu_debug.h

@@ -23,6 +23,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#define MAX_VOICE_WORKERS 16
+
 typedef enum McpxApuDebugMonitorPoint {
     MCPX_APU_DEBUG_MON_AC97,
     MCPX_APU_DEBUG_MON_VP,
@@ -55,10 +57,11 @@ struct McpxApuDebugVoice
 struct McpxApuDebugVp
 {
     struct McpxApuDebugVoice v[256];
+    int num_workers;
     struct {
         int num_voices;
         int time_us;
-    } workers[16];
+    } workers[MAX_VOICE_WORKERS];
     int total_worker_time_us;
 };
 

hw/xbox/mcpx/apu/vp/vp.c

@@ -1717,7 +1717,7 @@ static void voice_work_schedule(MCPXAPUState *d)
 
         if (!group) {
             next_worker_to_schedule =
-                (next_worker_to_schedule + 1) % NUM_VOICE_WORKERS;
+                (next_worker_to_schedule + 1) % vwd->num_workers;
         }
     }
 }
@@ -1761,15 +1761,20 @@ static void voice_work_init(MCPXAPUState *d)
 {
     VoiceWorkDispatch *vwd = &d->vp.voice_work_dispatch;
 
+    int num_workers = g_config.audio.vp.num_workers ?: SDL_GetCPUCount();
+    vwd->num_workers = MAX(1, MIN(num_workers, MAX_VOICE_WORKERS));
+    vwd->workers = g_malloc0_n(vwd->num_workers, sizeof(VoiceWorker));
     vwd->workers_should_exit = false;
     vwd->workers_pending = 0;
     vwd->queue_len = 0;
 
+    g_dbg.vp.num_workers = vwd->num_workers;
+
     qemu_mutex_init(&vwd->lock);
     qemu_mutex_lock(&vwd->lock);
     qemu_cond_init(&vwd->work_pending);
     qemu_cond_init(&vwd->work_finished);
-    for (int i = 0; i < NUM_VOICE_WORKERS; i++) {
+    for (int i = 0; i < vwd->num_workers; i++) {
         vwd->workers_pending |= 1 << i;
         qemu_thread_create(&vwd->workers[i].thread, "mcpx.voice_worker",
                            voice_worker_thread, d, QEMU_THREAD_JOINABLE);
@@ -1787,9 +1792,11 @@ static void voice_work_finalize(MCPXAPUState *d)
     vwd->workers_should_exit = true;
     qemu_cond_broadcast(&vwd->work_pending);
     qemu_mutex_unlock(&vwd->lock);
-    for (int i = 0; i < NUM_VOICE_WORKERS; i++) {
+    for (int i = 0; i < vwd->num_workers; i++) {
         qemu_thread_join(&vwd->workers[i].thread);
     }
+    g_free(vwd->workers);
+    vwd->workers = NULL;
 }
 
 void mcpx_apu_vp_frame(MCPXAPUState *d, float mixbins[NUM_MIXBINS][NUM_SAMPLES_PER_FRAME])

hw/xbox/mcpx/apu/vp/vp.h

@@ -31,8 +31,6 @@
 #include "svf.h"
 #include "hrtf.h"
 
-#define NUM_VOICE_WORKERS 16
-
 typedef struct MCPXAPUState MCPXAPUState;
 
 typedef struct MCPXAPUVPSSLData {
@@ -65,7 +63,8 @@ typedef struct VoiceWorker {
 
 typedef struct VoiceWorkDispatch {
     QemuMutex lock;
-    VoiceWorker workers[NUM_VOICE_WORKERS];
+    int num_workers;
+    VoiceWorker *workers;
     bool workers_should_exit;
     QemuCond work_pending;
     uint64_t workers_pending;

ui/xui/debug.cc

@@ -233,7 +233,7 @@ void DebugApuWindow::Draw()
         ImGui::Text(" W: #  us");
         ImGui::SameLine();
         ImGui::Text(" W: #  us");
-        for (int i = 0; i < 16; i++) {
+        for (int i = 0; i < dbg->vp.num_workers; i++) {
             if (i % 2) ImGui::SameLine();
             ImGui::Text("%2d:%2d %3d", i, dbg->vp.workers[i].num_voices,
                         dbg->vp.workers[i].time_us);