Le 25/02/2026 à 18:47, Shrikanth Hegde a écrit :
Hi Christophe.
I think I'm starting to understand now.
I think the problem is that acct->starttime has an invalid value the
very first time it is used.
We are probably lacking an initial value in paca->accounting.starttime.
This should likely be initialised from mftb in head_64.S in
start_here_common for main CPU and __secondary_start for other CPUs or
maybe at higher level in C in setup_arch() and start_secondary()
Christophe
How about below? this works too.
Fine it is works, it means we found the real problem.
What about using the newly added vtime_reset() ? See below (untested)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 9b3167274653..f4aef85106ac 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -377,7 +377,6 @@ void vtime_task_switch(struct task_struct *prev)
}
}
-#ifdef CONFIG_NO_HZ_COMMON
/**
* vtime_reset - Fast forward vtime entry clocks
*
@@ -394,6 +393,7 @@ void vtime_reset(void)
#endif
}
+#ifdef CONFIG_NO_HZ_COMMON
/**
* vtime_dyntick_start - Inform vtime about entry to idle-dynticks
*
@@ -931,6 +931,7 @@ static void __init set_decrementer_max(void)
static void __init init_decrementer_clockevent(void)
{
register_decrementer_clockevent(smp_processor_id());
+ vtime_reset();
}
void secondary_cpu_time_init(void)
@@ -946,6 +947,7 @@ void secondary_cpu_time_init(void)
/* FIME: Should make unrelated change to move snapshot_timebase
* call here ! */
register_decrementer_clockevent(smp_processor_id());
+ vtime_reset();
}
/*
---
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 18506740f4a4..af129645b7f7 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -928,9 +928,24 @@ static void __init set_decrementer_max(void)
bits, decrementer_max);
}
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+/*
+ * This is done to initialize the starttime correctly. with this
+ * /proc/stat show correct values similar to
CONFIG_VIRT_CPU_ACCOUNTING_GEN
+ */
+static void init_cpu_accounting_startime(void)
+{
+ struct cpu_accounting_data *acct = get_accounting(current);
+ acct->starttime = mftb();
+}
+#else
+static void init_cpu_accounting_startime(void) { };
+#endif
+
static void __init init_decrementer_clockevent(void)
{
register_decrementer_clockevent(smp_processor_id());
+ init_cpu_accounting_startime();
}
void secondary_cpu_time_init(void)
@@ -946,6 +961,8 @@ void secondary_cpu_time_init(void)
/* FIME: Should make unrelated change to move snapshot_timebase
* call here ! */
register_decrementer_clockevent(smp_processor_id());
+
+ init_cpu_accounting_startime();
}
/*
