From: Paul Clarke <hidden> Date: 2015-02-13 19:39:34
implement arch_irq_work_has_interrupt() for powerpc
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86 (3010279f)
and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
CC: Frederic Weisbecker <redacted>
CC: Paul E. McKenney <redacted>
Signed-off-by: Paul A. Clarke <redacted>
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..18365ec
From: Paul E. McKenney <hidden> Date: 2015-02-13 20:42:40
On Fri, Feb 13, 2015 at 01:38:36PM -0600, Paul Clarke wrote:
implement arch_irq_work_has_interrupt() for powerpc
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86
(3010279f) and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
CC: Frederic Weisbecker <redacted>
CC: Paul E. McKenney <redacted>
Signed-off-by: Paul A. Clarke <redacted>
Acked-by: Paul E. McKenney <redacted>
quoted hunk
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..18365ec
Regards,
Paul Clarke, IBM
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From: Michael Ellerman <mpe@ellerman.id.au> Date: 2015-02-16 00:08:42
On Fri, 2015-02-13 at 13:38 -0600, Paul Clarke wrote:
implement arch_irq_work_has_interrupt() for powerpc
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86 (3010279f)
and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
It makes the message change, but is that correct? ie. do we actually implement
"IRQ work self-IPIs"?
quoted hunk
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..18365ec
From: Benjamin Herrenschmidt <benh@kernel.crashing.org> Date: 2015-02-16 04:07:06
On Mon, 2015-02-16 at 11:08 +1100, Michael Ellerman wrote:
On Fri, 2015-02-13 at 13:38 -0600, Paul Clarke wrote:
quoted
implement arch_irq_work_has_interrupt() for powerpc
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86 (3010279f)
and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
.../...
It makes the message change, but is that correct? ie. do we actually implement
"IRQ work self-IPIs"?
I think so... Fred, do you think what we do will work ? We hijack our
decrementer (local timer) by making it shoot almost immediately (1 tick
away) and run the irq work at the beginning of __timer_interrupt().
At that point we are on our irq stack and have done irq_enter but that's
about it.
Cheers,
Ben.
quoted
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..18365ec
From: Paul Clarke <hidden> Date: 2015-02-20 17:08:47
implement arch_irq_work_has_interrupt() for powerpc
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86 (3010279f)
and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
v2: changed "return 1" to "return true", per Michael Ellerman
CC: Frederic Weisbecker <redacted>
CC: Paul E. McKenney <redacted>
Signed-off-by: Paul A. Clarke <redacted>
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..99cc0aa
From: Paul Clarke <hidden> Date: 2015-02-20 17:13:39
implement arch_irq_work_has_interrupt() for powerpc
(resending because I messed up the e-mail addresses)
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86 (3010279f)
and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
v2: changed "return 1" to "return true", per Michael Ellerman
CC: Frederic Weisbecker <redacted>
CC: Paul E. McKenney <redacted>
Signed-off-by: Paul A. Clarke <redacted>
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..99cc0aa
From: Paul E. McKenney <hidden> Date: 2015-02-21 05:18:52
On Fri, Feb 20, 2015 at 11:13:33AM -0600, Paul Clarke wrote:
implement arch_irq_work_has_interrupt() for powerpc
(resending because I messed up the e-mail addresses)
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86
(3010279f) and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
v2: changed "return 1" to "return true", per Michael Ellerman
CC: Frederic Weisbecker <redacted>
CC: Paul E. McKenney <redacted>
Signed-off-by: Paul A. Clarke <redacted>
Reviewed-by: Paul E. McKenney <redacted>
quoted hunk
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..99cc0aa
Hi Ben,
2015-02-16 5:06 GMT+01:00 Benjamin Herrenschmidt [off-list ref]:
On Mon, 2015-02-16 at 11:08 +1100, Michael Ellerman wrote:
quoted
On Fri, 2015-02-13 at 13:38 -0600, Paul Clarke wrote:
quoted
implement arch_irq_work_has_interrupt() for powerpc
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86 (3010279f)
and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
.../...
quoted
It makes the message change, but is that correct? ie. do we actually implement
"IRQ work self-IPIs"?
I think so... Fred, do you think what we do will work ? We hijack our
decrementer (local timer) by making it shoot almost immediately (1 tick
away) and run the irq work at the beginning of __timer_interrupt().
At that point we are on our irq stack and have done irq_enter but that's
about it.
Yes that should work. After all "self-IPI" is an oxymoron. One would
expect an IPI to be triggered by an irq controller but if such
operation isn't supported with the current CPU being both source and
destination, anything triggering the desired callback in an interrupt
context in a reasonable amount of time ahead does the job here.
I thought well that's what powerpc was doing for irq work but I wasn't
sure I understood the code correctly. I should have pinged people
about that, sorry.
Thanks.
Cheers,
Ben.
quoted
quoted
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..18365ec
From: Benjamin Herrenschmidt <benh@kernel.crashing.org> Date: 2015-02-22 22:30:38
On Sun, 2015-02-22 at 23:13 +0100, Frederic Weisbecker wrote:
Yes that should work. After all "self-IPI" is an oxymoron. One would
expect an IPI to be triggered by an irq controller but if such
operation isn't supported with the current CPU being both source and
destination, anything triggering the desired callback in an interrupt
context in a reasonable amount of time ahead does the job here.
We could do self-IPI on platforms that have an SMP-capable interrupt
controller too but it would probably have higher overhead and would
require verifying that the code for each of our different interrupt
controllers is safe to be called from NMIs (hint: ioremap space isn't
safe to access from NMIs for us on some CPU families...).
We might be able to do better than using the decrementer on some CPUs by
using local doorbells, but for now this will do.
I thought well that's what powerpc was doing for irq work but I wasn't
sure I understood the code correctly. I should have pinged people
about that, sorry.
From: Paul Clarke <hidden> Date: 2015-02-27 13:28:17
It appears the discussion wrapped up on this, favorably. Is there
anything else I need to do to get this merged?
Regards,
PC
On 02/20/2015 11:18 PM, Paul E. McKenney wrote:
On Fri, Feb 20, 2015 at 11:13:33AM -0600, Paul Clarke wrote:
quoted
implement arch_irq_work_has_interrupt() for powerpc
(resending because I messed up the e-mail addresses)
Commit 9b01f5bf3 introduced a dependency on "IRQ work self-IPIs" for
full dynamic ticks to be enabled, by expecting architectures to
implement a suitable arch_irq_work_has_interrupt() routine.
Several arches have implemented this routine, including x86
(3010279f) and arm (09f6edd4), but powerpc was omitted.
This patch implements this routine for powerpc.
The symptom, at boot (on powerpc arch systems) with "nohz_full=<CPU
list>" is displayed:
NO_HZ: Can't run full dynticks because arch doesn't support irq
work self-IPIs
after this patch:
NO_HZ: Full dynticks CPUs: <CPU list>.
Tested against 3.19.
v2: changed "return 1" to "return true", per Michael Ellerman
CC: Frederic Weisbecker <redacted>
CC: Paul E. McKenney <redacted>
Signed-off-by: Paul A. Clarke <redacted>
Reviewed-by: Paul E. McKenney <redacted>
quoted
diff --git a/arch/powerpc/include/asm/irq_work.h
b/arch/powerpc/include/asm/irq_work.h
new file mode 100644
index 0000000..99cc0aa