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authorEero Nurkkala <ext-eero.nurkkala@nokia.com>2009-10-07 10:54:26 +0200
committerThomas Gleixner <tglx@linutronix.de>2009-10-07 13:05:05 +0200
commitfdc6f192e7e1ae80565af23cc33dc88e3dcdf184 (patch)
tree431a47d5fe9b737cc5dd5fe40e178d06f7d579ed /kernel/time/tick-sched.c
parentMerge git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide-2.6 (diff)
downloadlinux-fdc6f192e7e1ae80565af23cc33dc88e3dcdf184.tar.xz
linux-fdc6f192e7e1ae80565af23cc33dc88e3dcdf184.zip
NOHZ: update idle state also when NOHZ is inactive
Commit f2e21c9610991e95621a81407cdbab881226419b had unfortunate side effects with cpufreq governors on some systems. If the system did not switch into NOHZ mode ts->inidle is not set when tick_nohz_stop_sched_tick() is called from the idle routine. Therefor all subsequent calls from irq_exit() to tick_nohz_stop_sched_tick() fail to call tick_nohz_start_idle(). This results in bogus idle accounting information which is passed to cpufreq governors. Set the inidle flag unconditionally of the NOHZ active state to keep the idle time accounting correct in any case. [ tglx: Added comment and tweaked the changelog ] Reported-by: Steven Noonan <steven@uplinklabs.net> Signed-off-by: Eero Nurkkala <ext-eero.nurkkala@nokia.com> Cc: Rik van Riel <riel@redhat.com> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Greg KH <greg@kroah.com> Cc: Steven Noonan <steven@uplinklabs.net> Cc: stable@kernel.org LKML-Reference: <1254907901.30157.93.camel@eenurkka-desktop> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time/tick-sched.c')
-rw-r--r--kernel/time/tick-sched.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e0f59a21c061..89aed5933ed4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -231,6 +231,13 @@ void tick_nohz_stop_sched_tick(int inidle)
if (!inidle && !ts->inidle)
goto end;
+ /*
+ * Set ts->inidle unconditionally. Even if the system did not
+ * switch to NOHZ mode the cpu frequency governers rely on the
+ * update of the idle time accounting in tick_nohz_start_idle().
+ */
+ ts->inidle = 1;
+
now = tick_nohz_start_idle(ts);
/*
@@ -248,8 +255,6 @@ void tick_nohz_stop_sched_tick(int inidle)
if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
goto end;
- ts->inidle = 1;
-
if (need_resched())
goto end;