Messages in this thread Patch in this message | | | Date | Thu, 17 Jun 2010 17:39:39 GMT | From | tip-bot for Peter Zijlstra <> | Subject | [tip:timers/urgent] nohz: Fix nohz ratelimit |
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Commit-ID: 3310d4d38fbc514e7b18bd3b1eea8effdd63b5aa Gitweb: http://git.kernel.org/tip/3310d4d38fbc514e7b18bd3b1eea8effdd63b5aa Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Thu, 17 Jun 2010 18:02:37 +0200 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Thu, 17 Jun 2010 19:37:29 +0200
nohz: Fix nohz ratelimit
Chris Wedgwood reports that 39c0cbe (sched: Rate-limit nohz) causes a serial console regression, unresponsiveness, and indeed it does. The reason is that the nohz code is skipped even when the tick was already stopped before the nohz_ratelimit(cpu) condition changed.
Move the nohz_ratelimit() check to the other conditions which prevent long idle sleeps.
Reported-by: Chris Wedgwood <cw@f00f.org> Tested-by: Brian Bloniarz <bmb@athenacr.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Greg KH <gregkh@suse.de> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Jef Driesen <jefdriesen@telenet.be> LKML-Reference: <1276790557.27822.516.camel@twins> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/time/tick-sched.c | 5 +---- 1 files changed, 1 insertions(+), 4 deletions(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 1d7b9bc..783fbad 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -315,9 +315,6 @@ void tick_nohz_stop_sched_tick(int inidle) goto end; } - if (nohz_ratelimit(cpu)) - goto end; - ts->idle_calls++; /* Read jiffies and the time when jiffies were updated last */ do { @@ -328,7 +325,7 @@ void tick_nohz_stop_sched_tick(int inidle) } while (read_seqretry(&xtime_lock, seq)); if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) || - arch_needs_cpu(cpu)) { + arch_needs_cpu(cpu) || nohz_ratelimit(cpu)) { next_jiffies = last_jiffies + 1; delta_jiffies = 1; } else {
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