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 <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Michael Ellerman <[email protected]> Cc: Heiko Carstens <[email protected]> Cc: Martin Schwidefsky <[email protected]> Cc: Tony Luck <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Stanislaw Gruszka <[email protected]> Cc: Wanpeng Li <[email protected]> Cc: Christian Borntraeger <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> --- 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
