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[PATCH 2/2] powerpc/mm: Enable page parallel initialisation

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  [PATCH 2/2] powerpc/mm: Enable page parallel initialisation Li Zhang <zhlcindy@gmail.com> - 2016-03-08 05:00 +0100
    Re: [PATCH 2/2] powerpc/mm: Enable page parallel initialisation Michael Ellerman <mpe@ellerman.id.au> - 2016-03-08 10:40 +0100
      Re: [PATCH 2/2] powerpc/mm: Enable page parallel initialisation Li Zhang <zhlcindy@gmail.com> - 2016-03-09 03:10 +0100
      Re: [PATCH 2/2] powerpc/mm: Enable page parallel initialisation Andrew Morton <akpm@linux-foundation.org> - 2016-03-09 22:50 +0100
        Re: [PATCH 2/2] powerpc/mm: Enable page parallel initialisation Michael Ellerman <mpe@ellerman.id.au> - 2016-03-10 01:30 +0100

#1352602 — [PATCH 2/2] powerpc/mm: Enable page parallel initialisation

From: Li Zhang <zhlcindy@linux.vnet.ibm.com>

Parallel initialisation has been enabled for X86, boot time is
improved greatly. On Power8, it is improved greatly for small
memory. Here is the result from my test on Power8 platform:

For 4GB memory: 57% is improved, boot time as the following:
with patch: 10s, without patch: 24.5s

For 50GB memory: 22% is improved, boot time as the following:
with patch: 43.8s, without patch: 56.8s

Acked-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
---
 * Add boot time details in change log.
 * Please apply this patch after [PATCH 1/2] mm: meminit: initialise
    more memory for inode/dentry hash tables in early boot, because
   [PATCH 1/2] is to fix a bug which can be reproduced on Power.

 arch/powerpc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 9faa18c..97d41ad 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -158,6 +158,7 @@ config PPC
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select HAVE_ARCH_SECCOMP_FILTER
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
-- 
2.1.0

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#1352797

Hi Li,

On Tue, 2016-03-08 at 11:55 +0800, Li Zhang wrote:

> From: Li Zhang <zhlcindy@linux.vnet.ibm.com>
>
> Parallel initialisation has been enabled for X86, boot time is
> improved greatly. On Power8, it is improved greatly for small
> memory. Here is the result from my test on Power8 platform:
>
> For 4GB memory: 57% is improved, boot time as the following:
> with patch: 10s, without patch: 24.5s

This isn't worded quite right, and the numbers are a bit off.

old = 24.5
new = 10

So the improvement is 14.5 (seconds).

That means the improvement (14.5) as a percentage of the original boot time is:

 = 14.5 / 24.5 * 100
 = 59.183673469387756
 = 59%

So you would say:

  For 4GB of memory, boot time is improved by 59%, from 24.5s to 10s.

> For 50GB memory: 22% is improved, boot time as the following:
> with patch: 43.8s, without patch: 56.8s

  For 50GB memory, boot time is improved by 22%, from 56.8s to 43.8s.

> Acked-by: Mel Gorman <mgorman@techsingularity.net>
> Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
> ---
>  * Add boot time details in change log.
>  * Please apply this patch after [PATCH 1/2] mm: meminit: initialise
>     more memory for inode/dentry hash tables in early boot, because
>    [PATCH 1/2] is to fix a bug which can be reproduced on Power.

Given that, I think it would be best if Andrew merged both of these patches.
Because this patch is pretty trivial, whereas the patch to mm/ is less so.

Is that OK Andrew?

For this one:

Acked-by: Michael Ellerman <mpe@ellerman.id.au>

cheers

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#1353721

On Tue, Mar 8, 2016 at 5:36 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> Hi Li,
>
> On Tue, 2016-03-08 at 11:55 +0800, Li Zhang wrote:
>
>> From: Li Zhang <zhlcindy@linux.vnet.ibm.com>
>>
>> Parallel initialisation has been enabled for X86, boot time is
>> improved greatly. On Power8, it is improved greatly for small
>> memory. Here is the result from my test on Power8 platform:
>>
>> For 4GB memory: 57% is improved, boot time as the following:
>> with patch: 10s, without patch: 24.5s
>
> This isn't worded quite right, and the numbers are a bit off.
>
> old = 24.5
> new = 10
>
> So the improvement is 14.5 (seconds).
>
> That means the improvement (14.5) as a percentage of the original boot time is:
>
>  = 14.5 / 24.5 * 100
>  = 59.183673469387756
>  = 59%

Oh, sorry. It seems that I made a mistake.
>
> So you would say:
>
>   For 4GB of memory, boot time is improved by 59%, from 24.5s to 10s.

Got it. :)

>
>> For 50GB memory: 22% is improved, boot time as the following:
>> with patch: 43.8s, without patch: 56.8s
>
>   For 50GB memory, boot time is improved by 22%, from 56.8s to 43.8s.
>
>> Acked-by: Mel Gorman <mgorman@techsingularity.net>
>> Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
>> ---
>>  * Add boot time details in change log.
>>  * Please apply this patch after [PATCH 1/2] mm: meminit: initialise
>>     more memory for inode/dentry hash tables in early boot, because
>>    [PATCH 1/2] is to fix a bug which can be reproduced on Power.
>
> Given that, I think it would be best if Andrew merged both of these patches.
> Because this patch is pretty trivial, whereas the patch to mm/ is less so.
>
> Is that OK Andrew?
>
> For this one:
>
> Acked-by: Michael Ellerman <mpe@ellerman.id.au>
>
> cheers
>



-- 

Best Regards
-Li

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#1354488

On Tue, 08 Mar 2016 20:36:34 +1100 Michael Ellerman <mpe@ellerman.id.au> wrote:

> Given that, I think it would be best if Andrew merged both of these patches.
> Because this patch is pretty trivial, whereas the patch to mm/ is less so.
> 
> Is that OK Andrew?

Yep, no probs.

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#1354709

On Wed, 2016-03-09 at 13:42 -0800, Andrew Morton wrote:
> On Tue, 08 Mar 2016 20:36:34 +1100 Michael Ellerman <mpe@ellerman.id.au> wrote:
>
> > Given that, I think it would be best if Andrew merged both of these patches.
> > Because this patch is pretty trivial, whereas the patch to mm/ is less so.
> >
> > Is that OK Andrew?
>
> Yep, no probs.

Thanks.

cheers

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