Hi Shrikanth,

Le 05/06/2026 à 05:03, Shrikanth Hegde a écrit :

Hi Christophe. Thanks for taking a look and review.

On 6/4/26 8:42 PM, Christophe Leroy (CS GROUP) wrote:

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Also, does this warrant Fixes tag? I found these two likely candidates.
Likely this issues exists since beginning.
c223c90386bc powerpc32: provide VIRT_CPU_ACCOUNTING

You say system has 240 CPU so I suppose this is not ppc32. That 
commit wsa not supposed to change anything for ppc64, did you 
identify anything special in that commit related to ppc64 ?

Yes. this was ppc64.

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b38a181c11d0 powerpc/time: isolate scaled cputime accounting in 
dedicated functions.

This one is also pure code re-organisation, unless you've been able 
to spot a particular issue ?

Maybe commit cf9efce0ce31 ("powerpc: Account time using timebase 
rather than PURR")

It removed snapshot_timebases() and I can't see anything to replace it.

Yes. But this patch is dependent on Frederic's series.
backporting that is going to be difficult. So i am thinking to avoid 
putting Fixes tag.

Even if automatic backport will fail, it shouldn't be difficult to 
perform a manual backport by just adding the missing vtime_reset().
So I would put the Fixes tag to make people award.

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  arch/powerpc/kernel/time.c | 4 +++-
  1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 3460d1a5a97c..11145c40183d 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
   *

@@ -933,6 +933,7 @@ 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)

@@ -948,6 +949,7 @@ 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();
  }
  /*

Sorry i should have put this earlier, But this applies on top of tip/ 
timers/nohz
at 6199f9999a9b (origin/timers/nohz) sched/cputime: Handle dyntick-idle 
steal time correctly
(In case anyone tried applying on powerpc tree, it would fail)

Yep, I first looked vtime_reset() into linus tree, then found it in 
linux-next.

Christophe