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sched: Revert nohz_ratelimit() which causes a lot of extra wakeups burning CPU, and my legs.

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This commit is contained in:
Dave Jones 2010-08-04 15:06:07 -04:00
parent 4d5b945030
commit 4326aa56d8
2 changed files with 84 additions and 1 deletions
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10
kernel.spec
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@ -48,7 +48,7 @@ Summary: The Linux kernel
# reset this by hand to 1 (or to 0 and then use rpmdev-bumpspec).
# scripts/rebase.sh should be made to do that for you, actually.
#
%global baserelease 1
%global baserelease 2
%global fedora_build %{baserelease}
# base_sublevel is the kernel version we're starting with and patching
@ -597,6 +597,8 @@ Patch09: linux-2.6-upstream-reverts.patch
# Standalone patches
Patch20: linux-2.6-hotfixes.patch
Patch21: linux-2.6-tip.git-396e894d289d69bacf5acd983c97cd6e21a14c08.patch
Patch30: git-utrace.patch
Patch31: utrace-ptrace-fix-build.patch
Patch32: utrace-remove-use-of-kref_set.patch
@ -1118,6 +1120,8 @@ ApplyOptionalPatch linux-2.6-upstream-reverts.patch -R
ApplyPatch linux-2.6-hotfixes.patch
ApplyPatch linux-2.6-tip.git-396e894d289d69bacf5acd983c97cd6e21a14c08.patch
# Roland's utrace ptrace replacement.
ApplyPatch git-utrace.patch
ApplyPatch utrace-ptrace-fix-build.patch
@ -1877,6 +1881,10 @@ fi
# || ||
%changelog
* Wed Aug 04 2010 Dave Jones <davej@redhat.com>
- sched: Revert nohz_ratelimit() which causes a lot of
extra wakeups burning CPU, and my legs.
* Sun Aug 01 2010 Dave Jones <davej@redhat.com>
- Linux 2.6.35

75
linux-2.6-tip.git-396e894d289d69bacf5acd983c97cd6e21a14c08.patch Normal file
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@ -0,0 +1,75 @@
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 9 Jul 2010 13:12:27 +0000 (+0200)
Subject: sched: Revert nohz_ratelimit() for now
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fx86%2Flinux-2.6-tip.git;a=commitdiff_plain;h=396e894d289d69bacf5acd983c97cd6e21a14c08
sched: Revert nohz_ratelimit() for now
Norbert reported that nohz_ratelimit() causes his laptop to burn about
4W (40%) extra. For now back out the change and see if we can adjust
the power management code to make better decisions.
Reported-by: Norbert Preining <preining@logic.at>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 747fcae..6e0bb86 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -273,17 +273,11 @@ extern cpumask_var_t nohz_cpu_mask;
#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ)
extern int select_nohz_load_balancer(int cpu);
extern int get_nohz_load_balancer(void);
-extern int nohz_ratelimit(int cpu);
#else
static inline int select_nohz_load_balancer(int cpu)
{
return 0;
}
-
-static inline int nohz_ratelimit(int cpu)
-{
- return 0;
-}
#endif
/*
diff --git a/kernel/sched.c b/kernel/sched.c
index f52a880..63b4a14 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1232,16 +1232,6 @@ void wake_up_idle_cpu(int cpu)
smp_send_reschedule(cpu);
}
-int nohz_ratelimit(int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- u64 diff = rq->clock - rq->nohz_stamp;
-
- rq->nohz_stamp = rq->clock;
-
- return diff < (NSEC_PER_SEC / HZ) >> 1;
-}
-
#endif /* CONFIG_NO_HZ */
static u64 sched_avg_period(void)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 813993b..f898af6 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -325,7 +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) || nohz_ratelimit(cpu)) {
+ arch_needs_cpu(cpu)) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {