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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2010-05-17 12:00:03 +0400
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-05-17 12:00:15 +0400
commit6377981faf1a4425b0531e577736ef03df97c8f6 (patch)
treef690c5d357413cb6f26c8463519ad2b1f8800851 /drivers/s390/cio
parent6a2df3a87276cdc08fd87070d09ea18d1fb9d622 (diff)
downloadlinux-6377981faf1a4425b0531e577736ef03df97c8f6.tar.xz
[S390] idle time accounting vs. machine checks
A machine check can interrupt the i/o and external interrupt handler anytime. If the machine check occurs while the interrupt handler is waking up from idle vtime_start_cpu can get executed a second time and the int_clock / async_enter_timer values in the lowcore get clobbered. This can confuse the cpu time accounting. To fix this problem two changes are needed. First the machine check handler has to use its own copies of int_clock and async_enter_timer, named mcck_clock and mcck_enter_timer. Second the nested execution of vtime_start_cpu has to be prevented. This is done in s390_idle_check by checking the wait bit in the program status word. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/cio')
-rw-r--r--drivers/s390/cio/cio.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 5feea1a371e1..f4e6cf3aceb8 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -616,7 +616,8 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
struct pt_regs *old_regs;
old_regs = set_irq_regs(regs);
- s390_idle_check();
+ s390_idle_check(regs, S390_lowcore.int_clock,
+ S390_lowcore.async_enter_timer);
irq_enter();
__get_cpu_var(s390_idle).nohz_delay = 1;
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)