Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 01/10] powerpc32: Fix stale scaled stime on context switch | Date | Thu, 5 Jan 2017 18:11:41 +0100 |
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On context switch with powerpc32, the cputime is accumulated in the thread_info struct. So the switching-in task must move forward its start time snapshot to the current time in order to later compute the delta spent in system mode.
This is what we do for the normal cputime by initializing the starttime field to the value of the previous task's starttime which got freshly updated.
But we are missing the update of the scaled cputime start time. As a result we may be accounting too much scaled cputime later.
Fix this by initializing the scaled cputime the same way we do for normal cputime.
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@kernel.org> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> --- arch/powerpc/kernel/time.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index bc2e08d..ce21650 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -407,6 +407,7 @@ void arch_vtime_task_switch(struct task_struct *prev) struct cpu_accounting_data *acct = get_accounting(current); acct->starttime = get_accounting(prev)->starttime; + acct->startspurr = get_accounting(prev)->startspurr; acct->system_time = 0; acct->user_time = 0; } -- 2.7.4
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