RK3326: gameplay priority and RetroArch tuning from the dArkOS analysis

- Launch emulators at nice -19 like dArkOS does; with the full-preempt
  kernel this keeps frame pacing stable when background work wakes up
  mid-frame.
- audio_latency 64 to 128, matching dArkOS on the same alsathread
  driver and hardware: the 64ms buffer underruns audibly on heavy
  cores, which users read as instability.
- fastforward_frameskip on: skip rendering during fast-forward and give
  the GPU time back to the core.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

projects/ArchR/packages/archr/sources/scripts/runemu.sh

@@ -485,7 +485,11 @@ if [[ "${ROMNAME}" == *".sh" ]] && [ ! "${PLATFORM}" = "ports" ] && [ ! "${PLATF
         ret_error=$?
 else
         ${VERBOSE} && log $0 "Executing $(eval echo ${RUNTHIS})"
-        eval ${RUNTHIS} &>>${OUTPUT_LOG}
+        # Launch the emulator at high priority: with the full-preempt
+        # kernel this keeps frame pacing stable when background work
+        # (udev, journald, wifi) wakes up mid-frame. Same value dArkOS
+        # uses for its emulators.
+        eval nice -n -19 ${RUNTHIS} &>>${OUTPUT_LOG}
         ret_error=$?
 fi
 

projects/ArchR/packages/emulators/libretro/retroarch/sources/RK3326/retroarch.cfg

@@ -23,7 +23,9 @@ audio_enable_menu_ok = "false"
 audio_enable = "true"
 audio_fastforward_mute = "false"
 audio_filter_dir = "~/.config/retroarch/filters/audio"
-audio_latency = "64"
+# 128 matches dArkOS on the same hardware/driver (alsathread): the 64ms
+# buffer underruns audibly on heavy cores, which users read as instability.
+audio_latency = "128"
 audio_max_timing_skew = "0.049999"
 audio_mixer_mute_enable = "false"
 audio_mixer_volume = "0.000000"
@@ -820,3 +822,6 @@ xmb_shadows_enable = "true"
 xmb_theme = "0"
 xmb_vertical_thumbnails = "false"
 youtube_stream_key = ""
+
+# skip render during fast-forward (GPU time back to the core)
+fastforward_frameskip = "true"