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[PATCH v2 4/4] arm64: add a new document for the fine-tuning tips

Huang Shijie posted 4 patches 1 year, 2 months ago
There is a newer version of this series
[PATCH v2 4/4] arm64: add a new document for the fine-tuning tips
Posted by Huang Shijie 1 year, 2 months ago 
Put some fine-tuning tips in this file:
	1.) rodata=noalias
	2.) slab_strict_numa
	3.) CONFIG_SCHED_CLUSTER

We can add more tips in future.

Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
---
 Documentation/arch/arm64/fine-tuning-tips.rst | 23 +++++++++++++++++++
 Documentation/arch/arm64/index.rst            |  1 +
 2 files changed, 24 insertions(+)
 create mode 100644 Documentation/arch/arm64/fine-tuning-tips.rst

diff --git a/Documentation/arch/arm64/fine-tuning-tips.rst b/Documentation/arch/arm64/fine-tuning-tips.rst
new file mode 100644
index 000000000000..70ef1cef92fb
--- /dev/null
+++ b/Documentation/arch/arm64/fine-tuning-tips.rst
@@ -0,0 +1,23 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+fine-tuning tips
+================
+
+This file contains some fine-tuning tips for arm64 machines.
+These tips do not gurantee that you can get better performance,
+but you can try them with your workload.
+
+rodata=noalias
+----------------
+It can provide us more block mappings and contiguous hits
+to map the linear region which minimizes the TLB footprint.
+
+slab_strict_numa
+----------------
+In NUMA, it will provide the local memory allocation by SLUB.
+
+CONFIG_SCHED_CLUSTER
+----------------
+Some arm64 machines have cpu core cluster, enable it may
+helps you get better performance.
diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst
index 6a012c98bdcd..36d1ef09bd71 100644
--- a/Documentation/arch/arm64/index.rst
+++ b/Documentation/arch/arm64/index.rst
@@ -16,6 +16,7 @@ ARM64 Architecture
     cpu-feature-registers
     cpu-hotplug
     elf_hwcaps
+    fine-tuning-tips
     gcs
     hugetlbpage
     kdump
-- 
2.40.1
Re: [PATCH v2 4/4] arm64: add a new document for the fine-tuning tips
Posted by Anshuman Khandual 1 year, 2 months ago 
On 11/26/24 14:26, Huang Shijie wrote:
> Put some fine-tuning tips in this file:
> 	1.) rodata=noalias
> 	2.) slab_strict_numa
> 	3.) CONFIG_SCHED_CLUSTER
> 
> We can add more tips in future.
> 
> Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
> ---
>  Documentation/arch/arm64/fine-tuning-tips.rst | 23 +++++++++++++++++++
>  Documentation/arch/arm64/index.rst            |  1 +
>  2 files changed, 24 insertions(+)
>  create mode 100644 Documentation/arch/arm64/fine-tuning-tips.rst
> 
> diff --git a/Documentation/arch/arm64/fine-tuning-tips.rst b/Documentation/arch/arm64/fine-tuning-tips.rst
> new file mode 100644
> index 000000000000..70ef1cef92fb
> --- /dev/null
> +++ b/Documentation/arch/arm64/fine-tuning-tips.rst
> @@ -0,0 +1,23 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +================
> +fine-tuning tips
> +================
> +
> +This file contains some fine-tuning tips for arm64 machines.
> +These tips do not gurantee that you can get better performance,
> +but you can try them with your workload.
> +
> +rodata=noalias
> +----------------
> +It can provide us more block mappings and contiguous hits
> +to map the linear region which minimizes the TLB footprint.
> +
> +slab_strict_numa
> +----------------
> +In NUMA, it will provide the local memory allocation by SLUB.
> +
> +CONFIG_SCHED_CLUSTER
> +----------------
> +Some arm64 machines have cpu core cluster, enable it may
> +helps you get better performance.
> diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst
> index 6a012c98bdcd..36d1ef09bd71 100644
> --- a/Documentation/arch/arm64/index.rst
> +++ b/Documentation/arch/arm64/index.rst
> @@ -16,6 +16,7 @@ ARM64 Architecture
>      cpu-feature-registers
>      cpu-hotplug
>      elf_hwcaps
> +    fine-tuning-tips
>      gcs
>      hugetlbpage
>      kdump
Although the idea for such a file makes sense, to help system admins
tune the kernel command line for required behaviour, I am concerned
about the overall structure and scope for such a document. Should it
contain tips regarding all the subsystems on the platform, till what
extent these details should be described in there and then there are
so many aspects for a required behaviour etc ?

Besides maintaining such a document might also be very difficult as
well given how implementations will change over time thus requiring
different tuning etc. Hence kernel source might not be a place for
such a document.
Re: [PATCH v2 4/4] arm64: add a new document for the fine-tuning tips
Posted by Shijie Huang 1 year, 2 months ago 
On 2024/12/6 11:56, Anshuman Khandual wrote:
> On 11/26/24 14:26, Huang Shijie wrote:
>> Put some fine-tuning tips in this file:
>> 	1.) rodata=noalias
>> 	2.) slab_strict_numa
>> 	3.) CONFIG_SCHED_CLUSTER
>>
>> We can add more tips in future.
>>
>> Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
>> ---
>>   Documentation/arch/arm64/fine-tuning-tips.rst | 23 +++++++++++++++++++
>>   Documentation/arch/arm64/index.rst            |  1 +
>>   2 files changed, 24 insertions(+)
>>   create mode 100644 Documentation/arch/arm64/fine-tuning-tips.rst
>>
>> diff --git a/Documentation/arch/arm64/fine-tuning-tips.rst b/Documentation/arch/arm64/fine-tuning-tips.rst
>> new file mode 100644
>> index 000000000000..70ef1cef92fb
>> --- /dev/null
>> +++ b/Documentation/arch/arm64/fine-tuning-tips.rst
>> @@ -0,0 +1,23 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +================
>> +fine-tuning tips
>> +================
>> +
>> +This file contains some fine-tuning tips for arm64 machines.
>> +These tips do not gurantee that you can get better performance,
>> +but you can try them with your workload.
>> +
>> +rodata=noalias
>> +----------------
>> +It can provide us more block mappings and contiguous hits
>> +to map the linear region which minimizes the TLB footprint.
>> +
>> +slab_strict_numa
>> +----------------
>> +In NUMA, it will provide the local memory allocation by SLUB.
>> +
>> +CONFIG_SCHED_CLUSTER
>> +----------------
>> +Some arm64 machines have cpu core cluster, enable it may
>> +helps you get better performance.
>> diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst
>> index 6a012c98bdcd..36d1ef09bd71 100644
>> --- a/Documentation/arch/arm64/index.rst
>> +++ b/Documentation/arch/arm64/index.rst
>> @@ -16,6 +16,7 @@ ARM64 Architecture
>>       cpu-feature-registers
>>       cpu-hotplug
>>       elf_hwcaps
>> +    fine-tuning-tips
>>       gcs
>>       hugetlbpage
>>       kdump
> Although the idea for such a file makes sense, to help system admins
> tune the kernel command line for required behaviour, I am concerned
This file also contains the CONFIG_SCHED_CLUSTER which is not a kernel 
command line.
> about the overall structure and scope for such a document. Should it
> contain tips regarding all the subsystems on the platform, till what
> extent these details should be described in there and then there are
> so many aspects for a required behaviour etc ?

My original thought is to let this file contains the tips only works in 
arm64.

All the tips which _may_ make the arm64 machines get better performance 
can be

recorded here.

Then the arm64 kernel engineers(the newbies) can follow this file, and 
ramp up

quickly.


>
> Besides maintaining such a document might also be very difficult as
> well given how implementations will change over time thus requiring
> different tuning etc. Hence kernel source might not be a place for
> such a document.

okay. If the kernel source is not the right place, I can remove this 
patch in next version.


Thanks

Huang Shijie
Re: [PATCH v2 4/4] arm64: add a new document for the fine-tuning tips
Posted by Christoph Lameter 1 year, 2 months ago 
On Tue, 26 Nov 2024, Huang Shijie wrote:

> +slab_strict_numa
> +----------------
> +In NUMA, it will provide the local memory allocation by SLUB.

"Slab objects will be placed individually according to memory policies. 
Increases object locality which is useful for NUMA systems using SLC 
caches"
[PATCH v2 4/4 fix] arm64: add a new document for the fine-tuning tips
Posted by Huang Shijie 1 year, 2 months ago 
Put some fine-tuning tips in this file:
	1.) rodata=noalias
	2.) slab_strict_numa
	3.) CONFIG_SCHED_CLUSTER

We can add more tips in future.

Signed-off-by: Huang Shijie <shijie@os.amperecomputing.com>
---
Add the comment from Christoph.
---
 Documentation/arch/arm64/fine-tuning-tips.rst | 25 +++++++++++++++++++
 Documentation/arch/arm64/index.rst            |  1 +
 2 files changed, 26 insertions(+)
 create mode 100644 Documentation/arch/arm64/fine-tuning-tips.rst

diff --git a/Documentation/arch/arm64/fine-tuning-tips.rst b/Documentation/arch/arm64/fine-tuning-tips.rst
new file mode 100644
index 000000000000..df67a5ac87b9
--- /dev/null
+++ b/Documentation/arch/arm64/fine-tuning-tips.rst
@@ -0,0 +1,25 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+fine-tuning tips
+================
+
+This file contains some fine-tuning tips for arm64 machines.
+These tips do not gurantee that you can get better performance,
+but you can try them with your workload.
+
+rodata=noalias
+----------------
+It can provide us more block mappings and contiguous hits
+to map the linear region which minimizes the TLB footprint.
+
+slab_strict_numa
+----------------
+In NUMA, it will provide the local memory allocation by SLUB.
+Slab objects will be placed individually according to memory policies.
+Increases object locality which is useful for NUMA systems using SLC caches.
+
+CONFIG_SCHED_CLUSTER
+----------------
+Some arm64 machines have cpu core clusters, enable it may
+helps you get better performance.
diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst
index 6a012c98bdcd..36d1ef09bd71 100644
--- a/Documentation/arch/arm64/index.rst
+++ b/Documentation/arch/arm64/index.rst
@@ -16,6 +16,7 @@ ARM64 Architecture
     cpu-feature-registers
     cpu-hotplug
     elf_hwcaps
+    fine-tuning-tips
     gcs
     hugetlbpage
     kdump
-- 
2.40.1

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