From 3310d4d38fbc514e7b18bd3b1eea8effdd63b5aa Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 17 Jun 2010 18:02:37 +0200 Subject: [PATCH] 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 Tested-by: Brian Bloniarz Signed-off-by: Mike Galbraith Signed-off-by: Peter Zijlstra Cc: Jiri Kosina Cc: Linus Torvalds Cc: Greg KH Cc: Alan Cox Cc: OGAWA Hirofumi Cc: Jef Driesen LKML-Reference: <1276790557.27822.516.camel@twins> Signed-off-by: Thomas Gleixner --- kernel/time/tick-sched.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 1d7b9bc1c034..783fbadf2202 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 { -- 2.20.1