fix(benchmark): use the correct subject for performance data

[kisvegabor]

Description of the feature or fix

Now each display has it's own subject.

Notes

• Update the Documentation if needed.
• Add Examples if relevant.
• Add Tests if applicable.
• If you added new options to lv_conf_template.h run lv_conf_internal_gen.py and update Kconfig.
• Run scripts/code-format.py (astyle version v3.4.12 needs to be installed) and follow the Code Conventions.
• Mark the Pull request as Draft while you are working on the first version, and mark is as Ready when it's ready for review.
• When changes were requested, re-request review to notify the maintainers.
• Help us to review this Pull Request! Anyone can approve or request changes.

[zjanosy]

Fixed.

[liamHowatt]

Update users of lv_global_t::sysmon_perf

diff --git a/demos/benchmark/lv_demo_benchmark.c b/demos/benchmark/lv_demo_benchmark.c
index 884378656..cd5b4bb12 100644
--- a/demos/benchmark/lv_demo_benchmark.c
+++ b/demos/benchmark/lv_demo_benchmark.c
@@ -418,8 +418,6 @@ static scene_dsc_t scenes[] = {
     {.name = "", .create_cb = NULL}
 };
 
-#define sysmon_perf LV_GLOBAL_DEFAULT()->sysmon_perf
-
 static uint32_t scene_act;
 static uint32_t rnd_act;
 
diff --git a/demos/music/lv_demo_music.c b/demos/music/lv_demo_music.c
index ab5ba6211..2f839d393 100644
--- a/demos/music/lv_demo_music.c
+++ b/demos/music/lv_demo_music.c
@@ -13,6 +13,9 @@
 #include "lv_demo_music_main.h"
 #include "lv_demo_music_list.h"
 #include "../../src/core/lv_global.h"
+#if LV_DEMO_MUSIC_AUTO_PLAY && LV_USE_PERF_MONITOR
+    #include "../../src/display/lv_display_private.h"
+#endif
 
 /*********************
  *      DEFINES
@@ -104,10 +107,6 @@ static const uint32_t time_list[] = {
     2 * 60 + 19,
 };
 
-#if LV_USE_PERF_MONITOR || LV_DEMO_MUSIC_AUTO_PLAY
-    #define sysmon_perf LV_GLOBAL_DEFAULT()->sysmon_perf
-#endif
-
 /**********************
  *      MACROS
  **********************/
@@ -230,7 +229,8 @@ static void auto_step_cb(lv_timer_t * t)
                 lv_obj_t * num = lv_label_create(bg);
                 lv_obj_set_style_text_font(num, font_large, 0);
 #if LV_USE_PERF_MONITOR
-                const lv_sysmon_perf_info_t * info = lv_subject_get_pointer(&sysmon_perf.subject);
+                lv_display_t * disp = lv_display_get_default();
+                const lv_sysmon_perf_info_t * info = lv_subject_get_pointer(&disp->perf_sysmon_backend.subject);
                 lv_label_set_text_fmt(num, "%" LV_PRIu32, info->calculated.fps_avg_total);
 #endif
                 lv_obj_align(num, LV_ALIGN_TOP_MID, 0, 120);

[kisvegabor]

Great catch! Updated.