[PATCH] x86_64: enable irq in default_idle

[PATCH] x86_64: enable irq in default_idle

[Hiroshi Shimamoto]

Hi Ingo,

I think local_irq_enable() is missing in default_idle() on x86_64.
It's for recent x86 tree.

From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Subject: [PATCH] x86_64: enable irq in default_idle

local_irq_enable() is missing after sched_clock_idle_wakeup_event().

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
---
 arch/x86/kernel/process_64.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c6ad1a0..93ce4f3 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -119,8 +119,8 @@ void default_idle(void)
 		t1 = ktime_get();
 		t1n = ktime_to_ns(t1);
 		sched_clock_idle_wakeup_event(t1n - t0n);
-	} else
-		local_irq_enable();
+	}
+	local_irq_enable();
 	current_thread_info()->status |= TS_POLLING;
 }
 
-- 
1.5.3.6

Re: [PATCH] x86_64: enable irq in default_idle

[Ingo Molnar]

* Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> wrote:

> Hi Ingo,
> 
> I think local_irq_enable() is missing in default_idle() on x86_64. 
> It's for recent x86 tree.
> 
> From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
> Subject: [PATCH] x86_64: enable irq in default_idle
> 
> local_irq_enable() is missing after sched_clock_idle_wakeup_event().

thanks Hiroshi, applied.

The effects of this bug should be increased latencies on 64-bit. Did you 
notice these latencies, or did you find the bug in some other way (code 
review)?

	Ingo

Re: [PATCH] x86_64: enable irq in default_idle

[Hiroshi Shimamoto]

Ingo Molnar wrote:
> * Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> wrote:
> 
>> Hi Ingo,
>>
>> I think local_irq_enable() is missing in default_idle() on x86_64. 
>> It's for recent x86 tree.
>>
>> From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
>> Subject: [PATCH] x86_64: enable irq in default_idle
>>
>> local_irq_enable() is missing after sched_clock_idle_wakeup_event().
> 
> thanks Hiroshi, applied.
> 
> The effects of this bug should be increased latencies on 64-bit. Did you 
> notice these latencies, or did you find the bug in some other way (code 
> review)?

I found this when I was comparing 32-bit and 64-bit source code
for x86 unification.

Thanks,
Hiroshi Shimamoto

Re: [PATCH] x86_64: enable irq in default_idle

[Ingo Molnar]

* Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> wrote:

> >> local_irq_enable() is missing after 
> >> sched_clock_idle_wakeup_event().
> > 
> > thanks Hiroshi, applied.
> > 
> > The effects of this bug should be increased latencies on 64-bit. Did 
> > you notice these latencies, or did you find the bug in some other 
> > way (code review)?
> 
> I found this when I was comparing 32-bit and 64-bit source code for 
> x86 unification.

cool :) Indeed even for other code, a number of times we got bugfixes 
when unifying 32-bit and 64-bit files.

	Ingo