Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting

Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting

[Frederic Weisbecker]

On Thu, Oct 03, 2013 at 06:58:03AM -0700, tip-bot for Kevin Hilman wrote:
> Commit-ID:  31c1fc8187158cb80ccd57c19e024c55af901797
> Gitweb:     http://git.kernel.org/tip/31c1fc8187158cb80ccd57c19e024c55af901797
> Author:     Kevin Hilman <khilman@linaro.org>
> AuthorDate: Mon, 16 Sep 2013 15:28:22 -0700
> Committer:  Frederic Weisbecker <fweisbec@gmail.com>
> CommitDate: Mon, 30 Sep 2013 15:37:05 +0200
> 
> ARM: Kconfig: allow full nohz CPU accounting
> 
> With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN,
> allow ARM platforms to enable it.  Since VIRT_CPU_ACCOUNTING_GEN is a
> dependency for full NO_HZ, this allows ARM platforms to enable full
> NO_HZ as well.

I realize that arm doesn't implement irq work raise. It hooks on the
timer to execute pending irq work. You'll need to implement arch_irq_work_raise()
and implement some sort of self IPI to trigger irq work. The full dynticks subsystem
relies on that to work correctly. It often use that to re-evaluate and possibly restart
the tick after scheduler, posix timer updates, etc...

That notwithstanding that if you have no tick, tick based irq work can't
work.

Thanks.

> 
> Signed-off-by: Kevin Hilman <khilman@linaro.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Russell King <rmk@arm.linux.org.uk>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Arm Linux <linux-arm-kernel@lists.infradead.org>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
>  arch/arm/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 1ad6fb6..323baf0 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -54,6 +54,7 @@ config ARM
>  	select HAVE_REGS_AND_STACK_ACCESS_API
>  	select HAVE_SYSCALL_TRACEPOINTS
>  	select HAVE_UID16
> +	select HAVE_VIRT_CPU_ACCOUNTING_GEN
>  	select IRQ_FORCED_THREADING
>  	select KTIME_SCALAR
>  	select MODULES_USE_ELF_REL

Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting

[Stephen Boyd]

On 10/16, Frederic Weisbecker wrote:
> On Thu, Oct 03, 2013 at 06:58:03AM -0700, tip-bot for Kevin Hilman wrote:
> > Commit-ID:  31c1fc8187158cb80ccd57c19e024c55af901797
> > Gitweb:     http://git.kernel.org/tip/31c1fc8187158cb80ccd57c19e024c55af901797
> > Author:     Kevin Hilman <khilman@linaro.org>
> > AuthorDate: Mon, 16 Sep 2013 15:28:22 -0700
> > Committer:  Frederic Weisbecker <fweisbec@gmail.com>
> > CommitDate: Mon, 30 Sep 2013 15:37:05 +0200
> > 
> > ARM: Kconfig: allow full nohz CPU accounting
> > 
> > With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN,
> > allow ARM platforms to enable it.  Since VIRT_CPU_ACCOUNTING_GEN is a
> > dependency for full NO_HZ, this allows ARM platforms to enable full
> > NO_HZ as well.
> 
> I realize that arm doesn't implement irq work raise. It hooks on the
> timer to execute pending irq work. You'll need to implement arch_irq_work_raise()
> and implement some sort of self IPI to trigger irq work. The full dynticks subsystem
> relies on that to work correctly. It often use that to re-evaluate and possibly restart
> the tick after scheduler, posix timer updates, etc...
> 
> That notwithstanding that if you have no tick, tick based irq work can't
> work.
> 

Something like this? The only problem is that this latches on to
the SMP support for IPIs. If CONFIG_SMP is disabled we won't get
arch_irq_work_raise() but perhaps that isn't so big of a deal? Or
we should think about exposing IPI support to UP systems on ARM.

----8<-----
 arch/arm/include/asm/hardirq.h |  2 +-
 arch/arm/kernel/smp.c          | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h
index 2740c2a2..3d7351c 100644
--- a/arch/arm/include/asm/hardirq.h
+++ b/arch/arm/include/asm/hardirq.h
@@ -5,7 +5,7 @@
 #include <linux/threads.h>
 #include <asm/irq.h>
 
-#define NR_IPI	6
+#define NR_IPI	7
 
 typedef struct {
 	unsigned int __softirq_pending;
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 72024ea..bf9a0d6d 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -25,6 +25,7 @@
 #include <linux/clockchips.h>
 #include <linux/completion.h>
 #include <linux/cpufreq.h>
+#include <linux/irq_work.h>
 
 #include <linux/atomic.h>
 #include <asm/smp.h>
@@ -66,6 +67,7 @@ enum ipi_msg_type {
 	IPI_CALL_FUNC,
 	IPI_CALL_FUNC_SINGLE,
 	IPI_CPU_STOP,
+	IPI_IRQ_WORK,
 };
 
 static DECLARE_COMPLETION(cpu_running);
@@ -448,6 +450,13 @@ void arch_send_call_function_single_ipi(int cpu)
 	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 }
 
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+	smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+}
+#endif
+
 static const char *ipi_types[NR_IPI] = {
 #define S(x,s)	[x] = s
 	S(IPI_WAKEUP, "CPU wakeup interrupts"),
@@ -456,6 +465,7 @@ static const char *ipi_types[NR_IPI] = {
 	S(IPI_CALL_FUNC, "Function call interrupts"),
 	S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 	S(IPI_CPU_STOP, "CPU stop interrupts"),
+	S(IPI_IRQ_WORK, "IRQ work interrupts"),
 };
 
 void show_ipi_list(struct seq_file *p, int prec)
@@ -565,6 +575,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 		irq_exit();
 		break;
 
+#ifdef CONFIG_IRQ_WORK
+	case IPI_IRQ_WORK:
+		irq_enter();
+		irq_work_run();
+		irq_exit();
+		break;
+#endif
+
 	default:
 		printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
 		       cpu, ipinr);
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting

[Frederic Weisbecker]

2013/10/18 Stephen Boyd <sboyd@codeaurora.org>:
> On 10/16, Frederic Weisbecker wrote:
>> On Thu, Oct 03, 2013 at 06:58:03AM -0700, tip-bot for Kevin Hilman wrote:
>> > Commit-ID:  31c1fc8187158cb80ccd57c19e024c55af901797
>> > Gitweb:     http://git.kernel.org/tip/31c1fc8187158cb80ccd57c19e024c55af901797
>> > Author:     Kevin Hilman <khilman@linaro.org>
>> > AuthorDate: Mon, 16 Sep 2013 15:28:22 -0700
>> > Committer:  Frederic Weisbecker <fweisbec@gmail.com>
>> > CommitDate: Mon, 30 Sep 2013 15:37:05 +0200
>> >
>> > ARM: Kconfig: allow full nohz CPU accounting
>> >
>> > With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN,
>> > allow ARM platforms to enable it.  Since VIRT_CPU_ACCOUNTING_GEN is a
>> > dependency for full NO_HZ, this allows ARM platforms to enable full
>> > NO_HZ as well.
>>
>> I realize that arm doesn't implement irq work raise. It hooks on the
>> timer to execute pending irq work. You'll need to implement arch_irq_work_raise()
>> and implement some sort of self IPI to trigger irq work. The full dynticks subsystem
>> relies on that to work correctly. It often use that to re-evaluate and possibly restart
>> the tick after scheduler, posix timer updates, etc...
>>
>> That notwithstanding that if you have no tick, tick based irq work can't
>> work.
>>
>
> Something like this? The only problem is that this latches on to
> the SMP support for IPIs. If CONFIG_SMP is disabled we won't get
> arch_irq_work_raise() but perhaps that isn't so big of a deal? Or
> we should think about exposing IPI support to UP systems on ARM.
>
> ----8<-----
>  arch/arm/include/asm/hardirq.h |  2 +-
>  arch/arm/kernel/smp.c          | 18 ++++++++++++++++++
>  2 files changed, 19 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h
> index 2740c2a2..3d7351c 100644
> --- a/arch/arm/include/asm/hardirq.h
> +++ b/arch/arm/include/asm/hardirq.h
> @@ -5,7 +5,7 @@
>  #include <linux/threads.h>
>  #include <asm/irq.h>
>
> -#define NR_IPI 6
> +#define NR_IPI 7
>
>  typedef struct {
>         unsigned int __softirq_pending;
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 72024ea..bf9a0d6d 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -25,6 +25,7 @@
>  #include <linux/clockchips.h>
>  #include <linux/completion.h>
>  #include <linux/cpufreq.h>
> +#include <linux/irq_work.h>
>
>  #include <linux/atomic.h>
>  #include <asm/smp.h>
> @@ -66,6 +67,7 @@ enum ipi_msg_type {
>         IPI_CALL_FUNC,
>         IPI_CALL_FUNC_SINGLE,
>         IPI_CPU_STOP,
> +       IPI_IRQ_WORK,
>  };
>
>  static DECLARE_COMPLETION(cpu_running);
> @@ -448,6 +450,13 @@ void arch_send_call_function_single_ipi(int cpu)
>         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
>  }
>
> +#ifdef CONFIG_IRQ_WORK
> +void arch_irq_work_raise(void)
> +{
> +       smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
> +}
> +#endif
> +
>  static const char *ipi_types[NR_IPI] = {
>  #define S(x,s) [x] = s
>         S(IPI_WAKEUP, "CPU wakeup interrupts"),
> @@ -456,6 +465,7 @@ static const char *ipi_types[NR_IPI] = {
>         S(IPI_CALL_FUNC, "Function call interrupts"),
>         S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
>         S(IPI_CPU_STOP, "CPU stop interrupts"),
> +       S(IPI_IRQ_WORK, "IRQ work interrupts"),
>  };
>
>  void show_ipi_list(struct seq_file *p, int prec)
> @@ -565,6 +575,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
>                 irq_exit();
>                 break;
>
> +#ifdef CONFIG_IRQ_WORK
> +       case IPI_IRQ_WORK:
> +               irq_enter();
> +               irq_work_run();
> +               irq_exit();
> +               break;
> +#endif
> +
>         default:
>                 printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
>                        cpu, ipinr);

Yeah that looks good! Indeed it's no big deal if it only support SMP
for now since full dynticks only works on SMP. It might work on UP one
day but we are not yet rushing on that :)

Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting

[Kevin Hilman]

Hi Stephen,

On 10/18/2013 09:37 AM, Stephen Boyd wrote:
> On 10/16, Frederic Weisbecker wrote:
>> On Thu, Oct 03, 2013 at 06:58:03AM -0700, tip-bot for Kevin Hilman wrote:
>>> Commit-ID:  31c1fc8187158cb80ccd57c19e024c55af901797
>>> Gitweb:     http://git.kernel.org/tip/31c1fc8187158cb80ccd57c19e024c55af901797
>>> Author:     Kevin Hilman <khilman@linaro.org>
>>> AuthorDate: Mon, 16 Sep 2013 15:28:22 -0700
>>> Committer:  Frederic Weisbecker <fweisbec@gmail.com>
>>> CommitDate: Mon, 30 Sep 2013 15:37:05 +0200
>>>
>>> ARM: Kconfig: allow full nohz CPU accounting
>>>
>>> With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN,
>>> allow ARM platforms to enable it.  Since VIRT_CPU_ACCOUNTING_GEN is a
>>> dependency for full NO_HZ, this allows ARM platforms to enable full
>>> NO_HZ as well.
>>
>> I realize that arm doesn't implement irq work raise. It hooks on the
>> timer to execute pending irq work. You'll need to implement arch_irq_work_raise()
>> and implement some sort of self IPI to trigger irq work. The full dynticks subsystem
>> relies on that to work correctly. It often use that to re-evaluate and possibly restart
>> the tick after scheduler, posix timer updates, etc...
>>
>> That notwithstanding that if you have no tick, tick based irq work can't
>> work.
>>
> 
> Something like this? The only problem is that this latches on to
> the SMP support for IPIs. If CONFIG_SMP is disabled we won't get
> arch_irq_work_raise() but perhaps that isn't so big of a deal? Or
> we should think about exposing IPI support to UP systems on ARM.

Care to submit a proper patch for this to LAKML?  or if you prefer I can
do it (keeping your authorship.)   We need this for proper full NOHZ
support on ARM.  Thanks.

Kevin

Re: [tip:timers/core] ARM: Kconfig: allow full nohz CPU accounting

[Stephen Boyd]

On 10/27/13 18:32, Kevin Hilman wrote:
> Hi Stephen,
>
> On 10/18/2013 09:37 AM, Stephen Boyd wrote:
>> On 10/16, Frederic Weisbecker wrote:
>>> On Thu, Oct 03, 2013 at 06:58:03AM -0700, tip-bot for Kevin Hilman wrote:
>>>> Commit-ID:  31c1fc8187158cb80ccd57c19e024c55af901797
>>>> Gitweb:     http://git.kernel.org/tip/31c1fc8187158cb80ccd57c19e024c55af901797
>>>> Author:     Kevin Hilman <khilman@linaro.org>
>>>> AuthorDate: Mon, 16 Sep 2013 15:28:22 -0700
>>>> Committer:  Frederic Weisbecker <fweisbec@gmail.com>
>>>> CommitDate: Mon, 30 Sep 2013 15:37:05 +0200
>>>>
>>>> ARM: Kconfig: allow full nohz CPU accounting
>>>>
>>>> With the 64-bit requirement removed from VIRT_CPU_ACCOUNTING_GEN,
>>>> allow ARM platforms to enable it.  Since VIRT_CPU_ACCOUNTING_GEN is a
>>>> dependency for full NO_HZ, this allows ARM platforms to enable full
>>>> NO_HZ as well.
>>> I realize that arm doesn't implement irq work raise. It hooks on the
>>> timer to execute pending irq work. You'll need to implement arch_irq_work_raise()
>>> and implement some sort of self IPI to trigger irq work. The full dynticks subsystem
>>> relies on that to work correctly. It often use that to re-evaluate and possibly restart
>>> the tick after scheduler, posix timer updates, etc...
>>>
>>> That notwithstanding that if you have no tick, tick based irq work can't
>>> work.
>>>
>> Something like this? The only problem is that this latches on to
>> the SMP support for IPIs. If CONFIG_SMP is disabled we won't get
>> arch_irq_work_raise() but perhaps that isn't so big of a deal? Or
>> we should think about exposing IPI support to UP systems on ARM.
> Care to submit a proper patch for this to LAKML?  or if you prefer I can
> do it (keeping your authorship.)   We need this for proper full NOHZ
> support on ARM.  Thanks.

Sure no problem. Let me write up some sort of commit text and I'll send
it off again.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

[PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Stephen Boyd]

This will allow the scheduler tick to be restarted if we're in
full NOHZ mode.

Cc: Kevin Hilman <khilman@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
 arch/arm/include/asm/hardirq.h |  2 +-
 arch/arm/kernel/smp.c          | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/hardirq.h b/arch/arm/include/asm/hardirq.h
index 2740c2a2..3d7351c 100644
--- a/arch/arm/include/asm/hardirq.h
+++ b/arch/arm/include/asm/hardirq.h
@@ -5,7 +5,7 @@
 #include <linux/threads.h>
 #include <asm/irq.h>
 
-#define NR_IPI	6
+#define NR_IPI	7
 
 typedef struct {
 	unsigned int __softirq_pending;
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 72024ea..bf9a0d6d 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -25,6 +25,7 @@
 #include <linux/clockchips.h>
 #include <linux/completion.h>
 #include <linux/cpufreq.h>
+#include <linux/irq_work.h>
 
 #include <linux/atomic.h>
 #include <asm/smp.h>
@@ -66,6 +67,7 @@ enum ipi_msg_type {
 	IPI_CALL_FUNC,
 	IPI_CALL_FUNC_SINGLE,
 	IPI_CPU_STOP,
+	IPI_IRQ_WORK,
 };
 
 static DECLARE_COMPLETION(cpu_running);
@@ -448,6 +450,13 @@ void arch_send_call_function_single_ipi(int cpu)
 	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
 }
 
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+	smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+}
+#endif
+
 static const char *ipi_types[NR_IPI] = {
 #define S(x,s)	[x] = s
 	S(IPI_WAKEUP, "CPU wakeup interrupts"),
@@ -456,6 +465,7 @@ static const char *ipi_types[NR_IPI] = {
 	S(IPI_CALL_FUNC, "Function call interrupts"),
 	S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
 	S(IPI_CPU_STOP, "CPU stop interrupts"),
+	S(IPI_IRQ_WORK, "IRQ work interrupts"),
 };
 
 void show_ipi_list(struct seq_file *p, int prec)
@@ -565,6 +575,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
 		irq_exit();
 		break;
 
+#ifdef CONFIG_IRQ_WORK
+	case IPI_IRQ_WORK:
+		irq_enter();
+		irq_work_run();
+		irq_exit();
+		break;
+#endif
+
 	default:
 		printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
 		       cpu, ipinr);
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Kevin Hilman]

Stephen Boyd <sboyd@codeaurora.org> writes:

> This will allow the scheduler tick to be restarted if we're in
> full NOHZ mode.
>
> Cc: Kevin Hilman <khilman@linaro.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

Minor nit, but I'd prefer a more verbose changelog (I forget things
quickly and like to rely on changelogs for my memory.)  Probably worth
adding something like: "By default, irq_work is tied to the tick
processing (update_process_times()) but in full NOHZ mode, no tick means
no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
self-IPI is used to process IRQ work."

Other than the changelog nit, patch looks good, feel free to add

Reviewed-by: Kevin Hilman <khilman@linaro.org>

If Russell is OK with this, it can go to his patch system.

Kevin

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Stephen Boyd]

On 10/28, Kevin Hilman wrote:
> Stephen Boyd <sboyd@codeaurora.org> writes:
> 
> > This will allow the scheduler tick to be restarted if we're in
> > full NOHZ mode.
> >
> > Cc: Kevin Hilman <khilman@linaro.org>
> > Cc: Frederic Weisbecker <fweisbec@gmail.com>
> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> 
> Minor nit, but I'd prefer a more verbose changelog (I forget things
> quickly and like to rely on changelogs for my memory.)  Probably worth
> adding something like: "By default, irq_work is tied to the tick
> processing (update_process_times()) but in full NOHZ mode, no tick means
> no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
> self-IPI is used to process IRQ work."
> 
> Other than the changelog nit, patch looks good, feel free to add
> 
> Reviewed-by: Kevin Hilman <khilman@linaro.org>
> 
> If Russell is OK with this, it can go to his patch system.
> 

Fair enough. This is what I came up with. I'll send it off to the
patch tracker in about 12 hours if nobody else has anymore
comments.

----8<-----
ARM: Support arch_irq_work_raise() via self IPIs                                

By default, IRQ work is run from the tick interrupt (see
irq_work_run() in update_process_times()). When we're in full
NOHZ mode, restarting the tick requires the use of IRQ work and
if the only place we run IRQ work is in the tick interrupt we
have an unbreakable cycle. Implement arch_irq_work_raise() via
self IPIs to break this cycle and get the tick started again.
Note that we implement this via IPIs which are only available on
SMP builds. This shouldn't be a problem because full NOHZ is only
supported on SMP builds anyway.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Frederic Weisbecker]

On Mon, Oct 28, 2013 at 11:00:58PM -0700, Stephen Boyd wrote:
> On 10/28, Kevin Hilman wrote:
> > Stephen Boyd <sboyd@codeaurora.org> writes:
> > 
> > > This will allow the scheduler tick to be restarted if we're in
> > > full NOHZ mode.
> > >
> > > Cc: Kevin Hilman <khilman@linaro.org>
> > > Cc: Frederic Weisbecker <fweisbec@gmail.com>
> > > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> > 
> > Minor nit, but I'd prefer a more verbose changelog (I forget things
> > quickly and like to rely on changelogs for my memory.)  Probably worth
> > adding something like: "By default, irq_work is tied to the tick
> > processing (update_process_times()) but in full NOHZ mode, no tick means
> > no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
> > self-IPI is used to process IRQ work."
> > 
> > Other than the changelog nit, patch looks good, feel free to add
> > 
> > Reviewed-by: Kevin Hilman <khilman@linaro.org>
> > 
> > If Russell is OK with this, it can go to his patch system.
> > 
> 
> Fair enough. This is what I came up with. I'll send it off to the
> patch tracker in about 12 hours if nobody else has anymore
> comments.
> 
> ----8<-----
> ARM: Support arch_irq_work_raise() via self IPIs                                
> 
> By default, IRQ work is run from the tick interrupt (see
> irq_work_run() in update_process_times()). When we're in full
> NOHZ mode, restarting the tick requires the use of IRQ work and
> if the only place we run IRQ work is in the tick interrupt we
> have an unbreakable cycle. Implement arch_irq_work_raise() via
> self IPIs to break this cycle and get the tick started again.
> Note that we implement this via IPIs which are only available on
> SMP builds. This shouldn't be a problem because full NOHZ is only
> supported on SMP builds anyway.

Nice description!

Thanks!

> 
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> Reviewed-by: Kevin Hilman <khilman@linaro.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> -- 
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Kevin Hilman]

Stephen Boyd <sboyd@codeaurora.org> writes:

> On 10/28, Kevin Hilman wrote:
>> Stephen Boyd <sboyd@codeaurora.org> writes:
>> 
>> > This will allow the scheduler tick to be restarted if we're in
>> > full NOHZ mode.
>> >
>> > Cc: Kevin Hilman <khilman@linaro.org>
>> > Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>> 
>> Minor nit, but I'd prefer a more verbose changelog (I forget things
>> quickly and like to rely on changelogs for my memory.)  Probably worth
>> adding something like: "By default, irq_work is tied to the tick
>> processing (update_process_times()) but in full NOHZ mode, no tick means
>> no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
>> self-IPI is used to process IRQ work."
>> 
>> Other than the changelog nit, patch looks good, feel free to add
>> 
>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>> 
>> If Russell is OK with this, it can go to his patch system.
>> 
>
> Fair enough. This is what I came up with. I'll send it off to the
> patch tracker in about 12 hours if nobody else has anymore
> comments.

Nice description, thanks for the respin.

Kevin

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Olof Johansson]

On Mon, Oct 28, 2013 at 11:00 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 10/28, Kevin Hilman wrote:
>> Stephen Boyd <sboyd@codeaurora.org> writes:
>>
>> > This will allow the scheduler tick to be restarted if we're in
>> > full NOHZ mode.
>> >
>> > Cc: Kevin Hilman <khilman@linaro.org>
>> > Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>
>> Minor nit, but I'd prefer a more verbose changelog (I forget things
>> quickly and like to rely on changelogs for my memory.)  Probably worth
>> adding something like: "By default, irq_work is tied to the tick
>> processing (update_process_times()) but in full NOHZ mode, no tick means
>> no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
>> self-IPI is used to process IRQ work."
>>
>> Other than the changelog nit, patch looks good, feel free to add
>>
>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>>
>> If Russell is OK with this, it can go to his patch system.
>>
>
> Fair enough. This is what I came up with. I'll send it off to the
> patch tracker in about 12 hours if nobody else has anymore
> comments.
>
> ----8<-----
> ARM: Support arch_irq_work_raise() via self IPIs
>
> By default, IRQ work is run from the tick interrupt (see
> irq_work_run() in update_process_times()). When we're in full
> NOHZ mode, restarting the tick requires the use of IRQ work and
> if the only place we run IRQ work is in the tick interrupt we
> have an unbreakable cycle. Implement arch_irq_work_raise() via
> self IPIs to break this cycle and get the tick started again.
> Note that we implement this via IPIs which are only available on
> SMP builds. This shouldn't be a problem because full NOHZ is only
> supported on SMP builds anyway.
>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> Reviewed-by: Kevin Hilman <khilman@linaro.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>


Hm, so I think this just landed in -next, which seems... late for
3.13. Anyway, it causes boot failures on Cubieboards (Allwinner A10),
I just bisected it down to this patch (fails to boot
multi_v7_defconfig, no console output at all).

Unfortunately I'm not getting any debug_ll output from the board at
the moment, so I can't actually get to a panic stack or other error
info. :( I hope I can get back to you with one later today.


-Olof

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Olof Johansson]

On Fri, Nov 8, 2013 at 12:06 PM, Olof Johansson <olof@lixom.net> wrote:
> On Mon, Oct 28, 2013 at 11:00 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> On 10/28, Kevin Hilman wrote:
>>> Stephen Boyd <sboyd@codeaurora.org> writes:
>>>
>>> > This will allow the scheduler tick to be restarted if we're in
>>> > full NOHZ mode.
>>> >
>>> > Cc: Kevin Hilman <khilman@linaro.org>
>>> > Cc: Frederic Weisbecker <fweisbec@gmail.com>
>>> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>>
>>> Minor nit, but I'd prefer a more verbose changelog (I forget things
>>> quickly and like to rely on changelogs for my memory.)  Probably worth
>>> adding something like: "By default, irq_work is tied to the tick
>>> processing (update_process_times()) but in full NOHZ mode, no tick means
>>> no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
>>> self-IPI is used to process IRQ work."
>>>
>>> Other than the changelog nit, patch looks good, feel free to add
>>>
>>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>>>
>>> If Russell is OK with this, it can go to his patch system.
>>>
>>
>> Fair enough. This is what I came up with. I'll send it off to the
>> patch tracker in about 12 hours if nobody else has anymore
>> comments.
>>
>> ----8<-----
>> ARM: Support arch_irq_work_raise() via self IPIs
>>
>> By default, IRQ work is run from the tick interrupt (see
>> irq_work_run() in update_process_times()). When we're in full
>> NOHZ mode, restarting the tick requires the use of IRQ work and
>> if the only place we run IRQ work is in the tick interrupt we
>> have an unbreakable cycle. Implement arch_irq_work_raise() via
>> self IPIs to break this cycle and get the tick started again.
>> Note that we implement this via IPIs which are only available on
>> SMP builds. This shouldn't be a problem because full NOHZ is only
>> supported on SMP builds anyway.
>>
>> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>
>
> Hm, so I think this just landed in -next, which seems... late for
> 3.13. Anyway, it causes boot failures on Cubieboards (Allwinner A10),
> I just bisected it down to this patch (fails to boot
> multi_v7_defconfig, no console output at all).
>
> Unfortunately I'm not getting any debug_ll output from the board at
> the moment, so I can't actually get to a panic stack or other error
> info. :( I hope I can get back to you with one later today.

Turns out that I hit this on the BeagleBone as well, and I got a trace
out of it. Seems like this might be broken on all non-SMP platforms
built with CONFIG_SMP=y?


[    0.206322] Unable to handle kernel NULL pointer dereference at
virtual address 00000000
[    0.214752] pgd = c0004000
[    0.217628] [00000000] *pgd=00000000
[    0.221421] Internal error: Oops: 80000005 [#1] SMP ARM
[    0.226890] Modules linked in:
[    0.230136] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
3.12.0-rc6-00018-g8d45144-dirty #16
[    0.238646] task: de05b440 ti: de05c000 task.ti: de05c000
[    0.244294] PC is at 0x0
[    0.247010] LR is at arch_irq_work_raise+0x3c/0x48
[    0.252034] pc : [<00000000>]    lr : [<c0019590>]    psr: 60000193
[    0.252034] sp : de05dd60  ip : 00000001  fp : 00000000
[    0.264029] r10: c085e2f0  r9 : de05c000  r8 : c07be0a4
[    0.269496] r7 : de05c000  r6 : de05c000  r5 : c07c5778  r4 : c0824554
[    0.276305] r3 : 00000000  r2 : 00000000  r1 : 00000006  r0 : c0529a58
[    0.283116] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM
Segment kernel
[    0.290818] Control: 10c5387d  Table: 80004019  DAC: 00000017
[    0.296821] Process swapper/0 (pid: 1, stack limit = 0xde05c248)
[    0.303094] Stack: (0xde05dd60 to 0xde05e000)
[    0.307677] dd60: c07b9dbc c00cb2dc 00000001 c08242c0 c08242c0
60000113 c07be0a8 c00b0590
[    0.316191] dd80: de05c000 c085e2f0 c08242c0 c08242c0 c1414c28
c00b07cc de05b440 c1414c28
[    0.324705] dda0: c08242c0 c00b0af8 c0862bb0 c0862db0 c1414cd8
de05c028 c0824840 de05ddb8
[    0.333218] ddc0: 00000000 00000009 00000001 00000024 c07be0a8
c07be0a4 de05c000 c085e2f0
[    0.341731] dde0: 00000000 c004a4b0 00000010 de00d2dc 00000054
00000100 00000024 00000000
[    0.350244] de00: de05c028 0000000a ffff8ae7 00200040 00000016
de05c000 60000193 de05c000
[    0.358756] de20: 00000054 00000000 00000000 00000000 00000000
c004a704 00000000 de05c008
[    0.367269] de40: c07ba254 c004aa1c c07c5778 c0014b70 fa200000
00000054 de05de80 c0861244
[    0.375782] de60: 00000000 c0008634 de05b440 c051c778 20000113
ffffffff de05deb4 c051d0a4
[    0.384295] de80: 00000001 00000001 00000000 de05b440 c082afac
de057ac0 de057ac0 de0443c0
[    0.392807] dea0: 00000000 00000000 00000000 00000000 c082afbc
de05dec8 c009f2a0 c051c778
[    0.401321] dec0: 20000113 ffffffff 00000000 c016edb0 00000000
000002b0 de057ac0 de057ac0
[    0.409833] dee0: 00000000 c016ee40 c0875e50 de05df2e de057ac0
00000000 00000013 00000000
[    0.418345] df00: 00000000 c016f054 de043600 de0443c0 c008eb38
de004ec0 c0875e50 c008eb44
[    0.426858] df20: 00000012 00000000 00000000 3931f0f8 00000000
00000000 00000014 c0822e84
[    0.435370] df40: 00000000 c008ed2c 00000000 00000000 00000000
c07b7490 c07b7490 c075ab3c
[    0.443882] df60: 00000000 c00701ac 00000002 00000000 c0070160
dffadb73 7bf8edb4 00000000
[    0.452394] df80: c051092c 00000000 00000000 00000000 00000000
00000000 00000000 c0510934
[    0.460907] dfa0: de05aa40 00000000 c051092c c0013ce8 00000000
00000000 00000000 00000000
[    0.469419] dfc0: 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000
[    0.477930] dfe0: 00000000 00000000 00000000 00000000 00000013
00000000 07efffe5 4dfac6f5
[    0.486468] [<c0019590>] (arch_irq_work_raise+0x3c/0x48) from
[<c00cb2dc>] (irq_work_queue+0xe4/0xf8)
[    0.496073] [<c00cb2dc>] (irq_work_queue+0xe4/0xf8) from
[<c00b0590>] (rcu_accelerate_cbs+0x1d4/0x1d8)
[    0.505756] [<c00b0590>] (rcu_accelerate_cbs+0x1d4/0x1d8) from
[<c00b07cc>] (rcu_start_gp+0x34/0x48)
[    0.515259] [<c00b07cc>] (rcu_start_gp+0x34/0x48) from [<c00b0af8>]
(rcu_process_callbacks+0x318/0x608)
[    0.525040] [<c00b0af8>] (rcu_process_callbacks+0x318/0x608) from
[<c004a4b0>] (__do_softirq+0x114/0x2a0)
[    0.534989] [<c004a4b0>] (__do_softirq+0x114/0x2a0) from
[<c004a704>] (do_softirq+0x6c/0x74)
[    0.543776] [<c004a704>] (do_softirq+0x6c/0x74) from [<c004aa1c>]
(irq_exit+0xac/0x100)
[    0.552126] [<c004aa1c>] (irq_exit+0xac/0x100) from [<c0014b70>]
(handle_IRQ+0x54/0xb4)
[    0.560466] [<c0014b70>] (handle_IRQ+0x54/0xb4) from [<c0008634>]
(omap3_intc_handle_irq+0x60/0x74)
[    0.569885] [<c0008634>] (omap3_intc_handle_irq+0x60/0x74) from
[<c051d0a4>] (__irq_svc+0x44/0x5c)
[    0.579196] Exception stack(0xde05de80 to 0xde05dec8)
[    0.584491] de80: 00000001 00000001 00000000 de05b440 c082afac
de057ac0 de057ac0 de0443c0
[    0.593004] dea0: 00000000 00000000 00000000 00000000 c082afbc
de05dec8 c009f2a0 c051c778
[    0.601510] dec0: 20000113 ffffffff
[    0.605202] [<c051d0a4>] (__irq_svc+0x44/0x5c) from [<c051c778>]
(_raw_spin_unlock_irq+0x28/0x2c)
[    0.614447] [<c051c778>] (_raw_spin_unlock_irq+0x28/0x2c) from
[<c016edb0>] (proc_alloc_inum+0x30/0xa8)
[    0.624220] [<c016edb0>] (proc_alloc_inum+0x30/0xa8) from
[<c016ee40>] (proc_register+0x18/0x130)
[    0.633454] [<c016ee40>] (proc_register+0x18/0x130) from
[<c016f054>] (proc_mkdir_data+0x44/0x6c)
[    0.642702] [<c016f054>] (proc_mkdir_data+0x44/0x6c) from
[<c008eb44>] (register_irq_proc+0x6c/0x128)
[    0.652292] [<c008eb44>] (register_irq_proc+0x6c/0x128) from
[<c008ed2c>] (init_irq_proc+0x74/0xb0)
[    0.661706] [<c008ed2c>] (init_irq_proc+0x74/0xb0) from
[<c075ab3c>] (kernel_init_freeable+0x84/0x1c8)
[    0.671390] [<c075ab3c>] (kernel_init_freeable+0x84/0x1c8) from
[<c0510934>] (kernel_init+0x8/0x150)
[    0.680892] [<c0510934>] (kernel_init+0x8/0x150) from [<c0013ce8>]
(ret_from_fork+0x14/0x2c)
[    0.689674] Code: bad PC value
[    0.692984] ---[ end trace 1b75b31a2719ed1c ]---

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Stephen Boyd]

On 11/08/13 12:45, Olof Johansson wrote:
> On Fri, Nov 8, 2013 at 12:06 PM, Olof Johansson <olof@lixom.net> wrote:
>> On Mon, Oct 28, 2013 at 11:00 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>>> On 10/28, Kevin Hilman wrote:
>>>> Stephen Boyd <sboyd@codeaurora.org> writes:
>>>>
>>>>> This will allow the scheduler tick to be restarted if we're in
>>>>> full NOHZ mode.
>>>>>
>>>>> Cc: Kevin Hilman <khilman@linaro.org>
>>>>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>>>>> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>>> Minor nit, but I'd prefer a more verbose changelog (I forget things
>>>> quickly and like to rely on changelogs for my memory.)  Probably worth
>>>> adding something like: "By default, irq_work is tied to the tick
>>>> processing (update_process_times()) but in full NOHZ mode, no tick means
>>>> no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
>>>> self-IPI is used to process IRQ work."
>>>>
>>>> Other than the changelog nit, patch looks good, feel free to add
>>>>
>>>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>>>>
>>>> If Russell is OK with this, it can go to his patch system.
>>>>
>>> Fair enough. This is what I came up with. I'll send it off to the
>>> patch tracker in about 12 hours if nobody else has anymore
>>> comments.
>>>
>>> ----8<-----
>>> ARM: Support arch_irq_work_raise() via self IPIs
>>>
>>> By default, IRQ work is run from the tick interrupt (see
>>> irq_work_run() in update_process_times()). When we're in full
>>> NOHZ mode, restarting the tick requires the use of IRQ work and
>>> if the only place we run IRQ work is in the tick interrupt we
>>> have an unbreakable cycle. Implement arch_irq_work_raise() via
>>> self IPIs to break this cycle and get the tick started again.
>>> Note that we implement this via IPIs which are only available on
>>> SMP builds. This shouldn't be a problem because full NOHZ is only
>>> supported on SMP builds anyway.
>>>
>>> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>>
>> Hm, so I think this just landed in -next, which seems... late for
>> 3.13. Anyway, it causes boot failures on Cubieboards (Allwinner A10),
>> I just bisected it down to this patch (fails to boot
>> multi_v7_defconfig, no console output at all).
>>
>> Unfortunately I'm not getting any debug_ll output from the board at
>> the moment, so I can't actually get to a panic stack or other error
>> info. :( I hope I can get back to you with one later today.
> Turns out that I hit this on the BeagleBone as well, and I got a trace
> out of it. Seems like this might be broken on all non-SMP platforms
> built with CONFIG_SMP=y?

Ah yes. We don't have IPI support on UP kernels but SMP_ON_UP exposes
arch_irq_work_raise(). How about this? We should just skip this function
if we're running on UP.

---8<----

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index bf9a0d6d..e115cbb 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -453,7 +453,8 @@ void arch_send_call_function_single_ipi(int cpu)
 #ifdef CONFIG_IRQ_WORK
 void arch_irq_work_raise(void)
 {
-	smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+	if (is_smp())
+		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
 }
 #endif
 


-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Olof Johansson]

On Fri, Nov 8, 2013 at 1:53 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 11/08/13 12:45, Olof Johansson wrote:
>> On Fri, Nov 8, 2013 at 12:06 PM, Olof Johansson <olof@lixom.net> wrote:
>>> On Mon, Oct 28, 2013 at 11:00 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>>>> On 10/28, Kevin Hilman wrote:
>>>>> Stephen Boyd <sboyd@codeaurora.org> writes:
>>>>>
>>>>>> This will allow the scheduler tick to be restarted if we're in
>>>>>> full NOHZ mode.
>>>>>>
>>>>>> Cc: Kevin Hilman <khilman@linaro.org>
>>>>>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>>>>>> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>>>> Minor nit, but I'd prefer a more verbose changelog (I forget things
>>>>> quickly and like to rely on changelogs for my memory.)  Probably worth
>>>>> adding something like: "By default, irq_work is tied to the tick
>>>>> processing (update_process_times()) but in full NOHZ mode, no tick means
>>>>> no IRQ work.  In order for IRQ work to be done in full NOHZ mode, a
>>>>> self-IPI is used to process IRQ work."
>>>>>
>>>>> Other than the changelog nit, patch looks good, feel free to add
>>>>>
>>>>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>>>>>
>>>>> If Russell is OK with this, it can go to his patch system.
>>>>>
>>>> Fair enough. This is what I came up with. I'll send it off to the
>>>> patch tracker in about 12 hours if nobody else has anymore
>>>> comments.
>>>>
>>>> ----8<-----
>>>> ARM: Support arch_irq_work_raise() via self IPIs
>>>>
>>>> By default, IRQ work is run from the tick interrupt (see
>>>> irq_work_run() in update_process_times()). When we're in full
>>>> NOHZ mode, restarting the tick requires the use of IRQ work and
>>>> if the only place we run IRQ work is in the tick interrupt we
>>>> have an unbreakable cycle. Implement arch_irq_work_raise() via
>>>> self IPIs to break this cycle and get the tick started again.
>>>> Note that we implement this via IPIs which are only available on
>>>> SMP builds. This shouldn't be a problem because full NOHZ is only
>>>> supported on SMP builds anyway.
>>>>
>>>> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
>>>> Reviewed-by: Kevin Hilman <khilman@linaro.org>
>>>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>>>
>>> Hm, so I think this just landed in -next, which seems... late for
>>> 3.13. Anyway, it causes boot failures on Cubieboards (Allwinner A10),
>>> I just bisected it down to this patch (fails to boot
>>> multi_v7_defconfig, no console output at all).
>>>
>>> Unfortunately I'm not getting any debug_ll output from the board at
>>> the moment, so I can't actually get to a panic stack or other error
>>> info. :( I hope I can get back to you with one later today.
>> Turns out that I hit this on the BeagleBone as well, and I got a trace
>> out of it. Seems like this might be broken on all non-SMP platforms
>> built with CONFIG_SMP=y?
>
> Ah yes. We don't have IPI support on UP kernels but SMP_ON_UP exposes
> arch_irq_work_raise(). How about this? We should just skip this function
> if we're running on UP.

Yep.

Tested-by: Olof Johansson <olof@lixom.net>

Send it to Russell's tracker, plz.


-Olof

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Stephen Boyd]

On 11/08/13 15:35, Olof Johansson wrote:
> On Fri, Nov 8, 2013 at 1:53 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>>
>> Ah yes. We don't have IPI support on UP kernels but SMP_ON_UP exposes
>> arch_irq_work_raise(). How about this? We should just skip this function
>> if we're running on UP.
> Yep.
>
> Tested-by: Olof Johansson <olof@lixom.net>
>
> Send it to Russell's tracker, plz.
>

Thanks. 7887/1.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Russell King - ARM Linux]

On Fri, Nov 08, 2013 at 03:39:13PM -0800, Stephen Boyd wrote:
> On 11/08/13 15:35, Olof Johansson wrote:
> > On Fri, Nov 8, 2013 at 1:53 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
> >>
> >> Ah yes. We don't have IPI support on UP kernels but SMP_ON_UP exposes
> >> arch_irq_work_raise(). How about this? We should just skip this function
> >> if we're running on UP.
> > Yep.
> >
> > Tested-by: Olof Johansson <olof@lixom.net>
> >
> > Send it to Russell's tracker, plz.
> >
> 
> Thanks. 7887/1.

It's probably going to miss Stephen's pull from my tree this evening (if
he even does one) so... that gives me two options: either drop the original
commit or apply this.

I think I'll apply this and put it in place just after the original commit
which caused the breakage.

Thanks.

Re: [PATCH] ARM: Support arch_irq_work_raise() via self IPIs

[Olof Johansson]

On Fri, Nov 8, 2013 at 4:01 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> On Fri, Nov 08, 2013 at 03:39:13PM -0800, Stephen Boyd wrote:
>> On 11/08/13 15:35, Olof Johansson wrote:
>> > On Fri, Nov 8, 2013 at 1:53 PM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> >>
>> >> Ah yes. We don't have IPI support on UP kernels but SMP_ON_UP exposes
>> >> arch_irq_work_raise(). How about this? We should just skip this function
>> >> if we're running on UP.
>> > Yep.
>> >
>> > Tested-by: Olof Johansson <olof@lixom.net>
>> >
>> > Send it to Russell's tracker, plz.
>> >
>>
>> Thanks. 7887/1.
>
> It's probably going to miss Stephen's pull from my tree this evening (if
> he even does one) so... that gives me two options: either drop the original
> commit or apply this.

It's Saturday for Stephen, so he won't do another one until Sunday
night our time.

> I think I'll apply this and put it in place just after the original commit
> which caused the breakage.

Thanks, sounds good to me.


-Olof