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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2016-12-20 07:27:59 +0100
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-12-20 15:22:56 +0100
commit8f2b468aadc81ca0fc78e41696b648e30d91ba5c (patch)
tree6908c5d1c11e29847a371567ed5ec09d08707bd4 /arch
parente93b1cc8a8965da137ffea0b88e5f62fa1d2a9e6 (diff)
downloadlinux-8f2b468aadc81ca0fc78e41696b648e30d91ba5c.tar.bz2
s390/vtime: correct system time accounting
There is a slight misaccounting of system time in vtime_account_user. This function is called once per HZ tick in interrupt context. The irq_enter function already accounted the system time up to the point of the irq_enter call. The system time from irq_enter until vtime_account_user/do_account_vtime is reached is irq time but it is accounted to the previous context. Just drop the hardirq offset from arch/s390/kernel/vtime.c. Reported-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/s390/kernel/vtime.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c
index 6b246aadf311..1b5c5ee9fc1b 100644
--- a/arch/s390/kernel/vtime.c
+++ b/arch/s390/kernel/vtime.c
@@ -94,7 +94,7 @@ static void update_mt_scaling(void)
* Update process times based on virtual cpu times stored by entry.S
* to the lowcore fields user_timer, system_timer & steal_clock.
*/
-static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
+static int do_account_vtime(struct task_struct *tsk)
{
u64 timer, clock, user, system, steal;
u64 user_scaled, system_scaled;
@@ -138,7 +138,7 @@ static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
}
account_user_time(tsk, user);
tsk->utimescaled += user_scaled;
- account_system_time(tsk, hardirq_offset, system);
+ account_system_time(tsk, 0, system);
tsk->stimescaled += system_scaled;
steal = S390_lowcore.steal_timer;
@@ -152,7 +152,7 @@ static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
void vtime_task_switch(struct task_struct *prev)
{
- do_account_vtime(prev, 0);
+ do_account_vtime(prev);
prev->thread.user_timer = S390_lowcore.user_timer;
prev->thread.system_timer = S390_lowcore.system_timer;
S390_lowcore.user_timer = current->thread.user_timer;
@@ -166,7 +166,7 @@ void vtime_task_switch(struct task_struct *prev)
*/
void vtime_account_user(struct task_struct *tsk)
{
- if (do_account_vtime(tsk, HARDIRQ_OFFSET))
+ if (do_account_vtime(tsk))
virt_timer_expire();
}