Changeset d9dda26 in mainline

Timestamp:

2022-08-15T13:33:01Z (2 years ago)

Author:

Jiří Zárevúcky <zarevucky.jiri@…>

Branches:

master, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

742f95ec

Parents:

0d59ea7e

git-author:

Jiří Zárevúcky <zarevucky.jiri@…> (2022-08-15 13:31:57)

git-committer:

Jiří Zárevúcky <zarevucky.jiri@…> (2022-08-15 13:33:01)

Message:

Update uptime using absolute count of clock ticks

Location:

kernel/generic

Files:

• include/cpu.h (modified) (1 diff)
• src/time/clock.c (modified) (4 diffs)

kernel/generic/include/cpu.h

@@ -74 +74 @@
         size_t missed_clock_ticks;
 
+        uint64_t current_clock_tick;
+
         /**
          * Processor cycle accounting.

kernel/generic/src/time/clock.c

@@ -65 +65 @@
 static parea_t clock_parea;
 
-/** Fragment of second
- *
- * For updating  seconds correctly.
- *
- */
-static sysarg_t secfrag = 0;
-
 /** Initialize realtime clock counter
  *
@@ -109 +102 @@
  *
  * Update it only on first processor
- * TODO: Do we really need so many write barriers?
- *
- */
-static void clock_update_counters(void)
+ */
+static void clock_update_counters(uint64_t current_tick)
 {
         if (CPU->id == 0) {
-                secfrag += 1000000 / HZ;
-                if (secfrag >= 1000000) {
-                        secfrag -= 1000000;
-                        uptime->seconds1++;
-                        write_barrier();
-                        uptime->useconds = secfrag;
-                        write_barrier();
-                        uptime->seconds2 = uptime->seconds1;
-                } else
-                        uptime->useconds += 1000000 / HZ;
+                uint64_t usec = (1000000 / HZ) * current_tick;
+
+                sysarg_t secs = usec / 1000000;
+                sysarg_t usecs = usec % 1000000;
+
+                uptime->seconds1 = secs;
+                write_barrier();
+                uptime->useconds = usecs;
+                write_barrier();
+                uptime->seconds2 = secs;
         }
 }
@@ -147 +138 @@
 {
         size_t missed_clock_ticks = CPU->missed_clock_ticks;
+        CPU->current_clock_tick += missed_clock_ticks + 1;
+        uint64_t current_clock_tick = CPU->current_clock_tick;
+        clock_update_counters(current_clock_tick);
 
         /* Account CPU usage */
@@ -159 +153 @@
         for (i = 0; i <= missed_clock_ticks; i++) {
                 /* Update counters and accounting */
-                clock_update_counters();
+
                 cpu_update_accounting();