Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-10 Thread Uwe Kleine-König 
On Wed, Sep 09, 2015 at 07:41:25AM +0200, Uwe Kleine-König wrote:
> On Tue, Sep 08, 2015 at 11:19:13PM +0100, Russell King - ARM Linux wrote:
> > On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
> > > This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
> > > when built for a single platform.
> > 
> > I'd prefer if we didn't do this, because this isn't supposed to be a user
> > visible "option".  It's an option that was introduced to avoid having to
> > throw masses of #ifdefs into the definition of MAX_ZONEORDER.
> > 
> > The problem with it is that it's a "well, what do I set this to?" option
> > and that leads to "oh, I'll just choose the default because I don't know
> > any better".
> > 
> > Do we know why EFM32 needs a value of 9 here?  It's not documented in
> > the original commit, and it really _should_ have been.
> IIRC it was done because of memory pressure. But not sure this makes any
> sense. I will try with the default value later today and report back.
I updated my patch stack to 4.2 and the difference between 9 and 11 is:

Using 9:

/ # free
 total used free   shared  buffers
Mem:  3744 1688 205600
-/+ buffers:   1688 2056

vs. using 11:

/ # free
 total used free   shared  buffers
Mem:  3744 1696 204800
-/+ buffers:   1696 2048

so it works with bearable costs. If you want to get rid of the special
casing for efm32 that's fine for me.

Best regards
Uwe

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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-10 Thread Uwe Kleine-König 
On Wed, Sep 09, 2015 at 07:41:25AM +0200, Uwe Kleine-König wrote:
> On Tue, Sep 08, 2015 at 11:19:13PM +0100, Russell King - ARM Linux wrote:
> > On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
> > > This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
> > > when built for a single platform.
> > 
> > I'd prefer if we didn't do this, because this isn't supposed to be a user
> > visible "option".  It's an option that was introduced to avoid having to
> > throw masses of #ifdefs into the definition of MAX_ZONEORDER.
> > 
> > The problem with it is that it's a "well, what do I set this to?" option
> > and that leads to "oh, I'll just choose the default because I don't know
> > any better".
> > 
> > Do we know why EFM32 needs a value of 9 here?  It's not documented in
> > the original commit, and it really _should_ have been.
> IIRC it was done because of memory pressure. But not sure this makes any
> sense. I will try with the default value later today and report back.
I updated my patch stack to 4.2 and the difference between 9 and 11 is:

Using 9:

/ # free
 total used free   shared  buffers
Mem:  3744 1688 205600
-/+ buffers:   1688 2056

vs. using 11:

/ # free
 total used free   shared  buffers
Mem:  3744 1696 204800
-/+ buffers:   1696 2048

so it works with bearable costs. If you want to get rid of the special
casing for efm32 that's fine for me.

Best regards
Uwe

-- 
Pengutronix e.K.   | Uwe Kleine-König|
Industrial Linux Solutions | http://www.pengutronix.de/  |
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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-09 Thread Maxime Coquelin 
2015-09-09 0:19 GMT+02:00 Russell King - ARM Linux :
> On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
>> This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
>> when built for a single platform.
>
> I'd prefer if we didn't do this, because this isn't supposed to be a user
> visible "option".  It's an option that was introduced to avoid having to
> throw masses of #ifdefs into the definition of MAX_ZONEORDER.
>
> The problem with it is that it's a "well, what do I set this to?" option
> and that leads to "oh, I'll just choose the default because I don't know
> any better".
>
> Do we know why EFM32 needs a value of 9 here?  It's not documented in
> the original commit, and it really _should_ have been.
Ok, I get your point.

For STM32, the value 11 is working, but having value of 9 makes sense
in my opinion for systems with small quantity of memory (8MB in the
case of STM32F429 Discovery).
It saves some bytes in the .data section, and it might also save some
CPU cycles as there are less iterations and less split/coalescing of
pages...
Note that for CPU cycles I haven't done any measurements, this is just
my opinion after code review.

What drawbacks do you see of using a value of 9?

Thanks,
Maxime
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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-09 Thread Maxime Coquelin 
2015-09-09 0:19 GMT+02:00 Russell King - ARM Linux :
> On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
>> This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
>> when built for a single platform.
>
> I'd prefer if we didn't do this, because this isn't supposed to be a user
> visible "option".  It's an option that was introduced to avoid having to
> throw masses of #ifdefs into the definition of MAX_ZONEORDER.
>
> The problem with it is that it's a "well, what do I set this to?" option
> and that leads to "oh, I'll just choose the default because I don't know
> any better".
>
> Do we know why EFM32 needs a value of 9 here?  It's not documented in
> the original commit, and it really _should_ have been.
Ok, I get your point.

For STM32, the value 11 is working, but having value of 9 makes sense
in my opinion for systems with small quantity of memory (8MB in the
case of STM32F429 Discovery).
It saves some bytes in the .data section, and it might also save some
CPU cycles as there are less iterations and less split/coalescing of
pages...
Note that for CPU cycles I haven't done any measurements, this is just
my opinion after code review.

What drawbacks do you see of using a value of 9?

Thanks,
Maxime
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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-08 Thread Uwe Kleine-König 
On Tue, Sep 08, 2015 at 11:19:13PM +0100, Russell King - ARM Linux wrote:
> On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
> > This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
> > when built for a single platform.
> 
> I'd prefer if we didn't do this, because this isn't supposed to be a user
> visible "option".  It's an option that was introduced to avoid having to
> throw masses of #ifdefs into the definition of MAX_ZONEORDER.
> 
> The problem with it is that it's a "well, what do I set this to?" option
> and that leads to "oh, I'll just choose the default because I don't know
> any better".
> 
> Do we know why EFM32 needs a value of 9 here?  It's not documented in
> the original commit, and it really _should_ have been.
IIRC it was done because of memory pressure. But not sure this makes any
sense. I will try with the default value later today and report back.

Best regards
Uwe

-- 
Pengutronix e.K.   | Uwe Kleine-König|
Industrial Linux Solutions | http://www.pengutronix.de/  |
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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-08 Thread Russell King - ARM Linux 
On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
> This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
> when built for a single platform.

I'd prefer if we didn't do this, because this isn't supposed to be a user
visible "option".  It's an option that was introduced to avoid having to
throw masses of #ifdefs into the definition of MAX_ZONEORDER.

The problem with it is that it's a "well, what do I set this to?" option
and that leads to "oh, I'll just choose the default because I don't know
any better".

Do we know why EFM32 needs a value of 9 here?  It's not documented in
the original commit, and it really _should_ have been.

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[PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-08 Thread Maxime Coquelin 
This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
when built for a single platform.

Suggested-by: Arnd Bergmann 
Signed-off-by: Maxime Coquelin 
---
 arch/arm/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a750c14..88937b9 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1731,10 +1731,10 @@ config ARM_MODULE_PLTS
 source "mm/Kconfig"
 
 config FORCE_MAX_ZONEORDER
-   int "Maximum zone order" if ARCH_SHMOBILE_LEGACY
+   int "Maximum zone order" if ARCH_SHMOBILE_LEGACY || ARM_SINGLE_ARMV7M
range 11 64 if ARCH_SHMOBILE_LEGACY
default "12" if SOC_AM33XX
-   default "9" if SA || ARCH_EFM32
+   default "9" if SA
default "11"
help
  The kernel memory allocator divides physically contiguous memory
-- 
1.9.1

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[PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-08 Thread Maxime Coquelin 
This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
when built for a single platform.

Suggested-by: Arnd Bergmann 
Signed-off-by: Maxime Coquelin 
---
 arch/arm/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a750c14..88937b9 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1731,10 +1731,10 @@ config ARM_MODULE_PLTS
 source "mm/Kconfig"
 
 config FORCE_MAX_ZONEORDER
-   int "Maximum zone order" if ARCH_SHMOBILE_LEGACY
+   int "Maximum zone order" if ARCH_SHMOBILE_LEGACY || ARM_SINGLE_ARMV7M
range 11 64 if ARCH_SHMOBILE_LEGACY
default "12" if SOC_AM33XX
-   default "9" if SA || ARCH_EFM32
+   default "9" if SA
default "11"
help
  The kernel memory allocator divides physically contiguous memory
-- 
1.9.1

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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-08 Thread Russell King - ARM Linux 
On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
> This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
> when built for a single platform.

I'd prefer if we didn't do this, because this isn't supposed to be a user
visible "option".  It's an option that was introduced to avoid having to
throw masses of #ifdefs into the definition of MAX_ZONEORDER.

The problem with it is that it's a "well, what do I set this to?" option
and that leads to "oh, I'll just choose the default because I don't know
any better".

Do we know why EFM32 needs a value of 9 here?  It's not documented in
the original commit, and it really _should_ have been.

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according to speedtest.net.
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Re: [PATCH v2 1/3] ARM: Make FORCE_MAX_ZONEORDER configurable if ARM_SINGLE_ARMV7M

2015-09-08 Thread Uwe Kleine-König 
On Tue, Sep 08, 2015 at 11:19:13PM +0100, Russell King - ARM Linux wrote:
> On Tue, Sep 08, 2015 at 10:38:04PM +0200, Maxime Coquelin wrote:
> > This patch makes FORCE_MAX_ZONEORDER configurable in defconfig for ARMV7-M
> > when built for a single platform.
> 
> I'd prefer if we didn't do this, because this isn't supposed to be a user
> visible "option".  It's an option that was introduced to avoid having to
> throw masses of #ifdefs into the definition of MAX_ZONEORDER.
> 
> The problem with it is that it's a "well, what do I set this to?" option
> and that leads to "oh, I'll just choose the default because I don't know
> any better".
> 
> Do we know why EFM32 needs a value of 9 here?  It's not documented in
> the original commit, and it really _should_ have been.
IIRC it was done because of memory pressure. But not sure this makes any
sense. I will try with the default value later today and report back.

Best regards
Uwe

-- 
Pengutronix e.K.   | Uwe Kleine-König|
Industrial Linux Solutions | http://www.pengutronix.de/  |
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