[PATCH v5] man2: add MPOL_WEIGHTED_INTERLEAVE documentation

[PATCH v5] man2: add MPOL_WEIGHTED_INTERLEAVE documentation

[Svetly Todorov]

---
Adding documentation for the new MPOL_WEIGHTED_INTERLEAVE mode in the same
manpages that mention MPOL_INTERLEAVE; namely, mbind(2), set_mempolicy(2),
and get_mempolicy(2).

Descriptions were based on the changes introduced in this patch: 
https://lore.kernel.org/all/20240202170238.90004-4-gregory.price@memverge.com/

Which was upstreamed to 6.9 here:
https://lore.kernel.org/linux-mm/20240313200532.34e4cff216acd3db8def4637@linux-foundation.org/

To: alx@kernel.org
Cc: linux-man@vger.kernel.org
Cc: gregory.price@memverge.com
Cc: ying.huang@intel.com
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Svetly Todorov <svetly.todorov@memverge.com>

Changes in v5:
- document kernel version where WEIGHTED_INTERLEAVE was added
- Link to v4: https://lore.kernel.org/r/20240316-weighted_interleave-v4-1-6ab516f12ced@memverge.com

Changes in v4:
- BR -> B in get_mempolicy
- use roman for ellipses; format using \|
- Link to v3: https://lore.kernel.org/r/20240315-weighted_interleave-v3-1-416a1ab01524@memverge.com

Changes in v3:
- italicize paths
- Link to v2: https://lore.kernel.org/r/20240315-weighted_interleave-v2-1-b742a48750b0@memverge.com

Changes in v2:
- make flag documentation implementation-agnostic
- Link to v1: https://lore.kernel.org/r/20240314-weighted_interleave-v1-1-ce85d64db0d4@memverge.com
---
 man2/get_mempolicy.2 | 12 ++++++++++--
 man2/mbind.2         | 18 ++++++++++++++++++
 man2/set_mempolicy.2 | 18 ++++++++++++++++++
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/man2/get_mempolicy.2 b/man2/get_mempolicy.2
index 5248f04ba..00ce287c9 100644
--- a/man2/get_mempolicy.2
+++ b/man2/get_mempolicy.2
@@ -137,7 +137,11 @@ specifies
 but not
 .BR MPOL_F_ADDR ,
 and the thread's current policy is
-.BR MPOL_INTERLEAVE ,
+.B MPOL_INTERLEAVE
+or
+.B MPOL_WEIGHTED_INTERLEAVE
+(available since Linux 6.9),
+.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
 then
 .BR get_mempolicy ()
 will return in the location pointed to by a non-NULL
@@ -206,7 +210,11 @@ specified
 but not
 .B MPOL_F_ADDR
 and the current thread policy is not
-.BR MPOL_INTERLEAVE .
+.B MPOL_INTERLEAVE
+or
+.B MPOL_WEIGHTED_INTERLEAVE
+(added in Linux 6.9).
+.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
 Or,
 .I flags
 specified
diff --git a/man2/mbind.2 b/man2/mbind.2
index b0e961f9c..6f2449946 100644
--- a/man2/mbind.2
+++ b/man2/mbind.2
@@ -105,6 +105,7 @@ argument must specify one of
 .BR MPOL_DEFAULT ,
 .BR MPOL_BIND ,
 .BR MPOL_INTERLEAVE ,
+.BR MPOL_WEIGHTED_INTERLEAVE ,
 .BR MPOL_PREFERRED ,
 or
 .B MPOL_LOCAL
@@ -243,6 +244,23 @@ at least 1\ MB or bigger with a fairly uniform access pattern.
 Accesses to a single page of the area will still be limited to
 the memory bandwidth of a single node.
 .TP
+.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
+.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
+This mode interleaves page allocations across the nodes specified in
+.I nodemask
+according to the weights in
+.IR /sys/kernel/mm/mempolicy/weighted_interleave .
+For example, if bits 0, 2, and 5 are raised in
+.IR nodemask ,
+and the contents of
+.IR /sys/kernel/mm/mempolicy/weighted_interleave/node0 ,
+.IR /sys/ .\|.\|. /node2 ,
+and
+.IR /sys/ .\|.\|. /node5
+are 4, 7, and 9, respectively,
+then pages in this region will be allocated on nodes 0, 2, and 5
+in a 4:7:9 ratio.
+.TP
 .B MPOL_PREFERRED
 This mode sets the preferred node for allocation.
 The kernel will try to allocate pages from this
diff --git a/man2/set_mempolicy.2 b/man2/set_mempolicy.2
index fc3ad9df8..3c08b6bf0 100644
--- a/man2/set_mempolicy.2
+++ b/man2/set_mempolicy.2
@@ -63,6 +63,7 @@ argument must specify one of
 .BR MPOL_DEFAULT ,
 .BR MPOL_BIND ,
 .BR MPOL_INTERLEAVE ,
+.BR MPOL_WEIGHTED_INTERLEAVE ,
 .BR MPOL_PREFERRED ,
 or
 .B MPOL_LOCAL
@@ -199,6 +200,23 @@ the memory bandwidth of a single node.
 .\" To be effective the memory area should be fairly large,
 .\" at least 1 MB or bigger.
 .TP
+.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
+.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
+This mode interleaves page allocations across the nodes specified in
+.I nodemask
+according to the weights in
+.IR /sys/kernel/mm/mempolicy/weighted_interleave .
+For example, if bits 0, 2, and 5 are raised in
+.IR nodemask ,
+and the contents of
+.IR /sys/kernel/mm/mempolicy/weighted_interleave/node0 ,
+.IR /sys/ .\|.\|. /node2 ,
+and
+.IR /sys/ .\|.\|. /node5
+are 4, 7, and 9, respectively,
+then pages in this region will be allocated on nodes 0, 2, and 5
+in a 4:7:9 ratio.
+.TP
 .B MPOL_PREFERRED
 This mode sets the preferred node for allocation.
 The kernel will try to allocate pages from this node first

---
base-commit: a4ea5f76215dcf1d8d017eb65ab12919ccf09f3f
change-id: 20240313-weighted_interleave-e8141ed754f9

Best regards,
-- 
Svetly Todorov <svetly.todorov@memverge.com>

Re: [PATCH v5] man2: add MPOL_WEIGHTED_INTERLEAVE documentation

[Alejandro Colomar]

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Hi Svetly,

On Mon, Mar 18, 2024 at 09:32:08AM -0700, Svetly Todorov wrote:
> ---
> Adding documentation for the new MPOL_WEIGHTED_INTERLEAVE mode in the same
> manpages that mention MPOL_INTERLEAVE; namely, mbind(2), set_mempolicy(2),
> and get_mempolicy(2).
> 
> Descriptions were based on the changes introduced in this patch: 
> https://lore.kernel.org/all/20240202170238.90004-4-gregory.price@memverge.com/
> 
> Which was upstreamed to 6.9 here:
> https://lore.kernel.org/linux-mm/20240313200532.34e4cff216acd3db8def4637@linux-foundation.org/
> 
> To: alx@kernel.org
> Cc: linux-man@vger.kernel.org
> Cc: gregory.price@memverge.com
> Cc: ying.huang@intel.com
> Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
> Signed-off-by: Svetly Todorov <svetly.todorov@memverge.com>
> 
> Changes in v5:
> - document kernel version where WEIGHTED_INTERLEAVE was added
> - Link to v4: https://lore.kernel.org/r/20240316-weighted_interleave-v4-1-6ab516f12ced@memverge.com
> 
> Changes in v4:
> - BR -> B in get_mempolicy
> - use roman for ellipses; format using \|
> - Link to v3: https://lore.kernel.org/r/20240315-weighted_interleave-v3-1-416a1ab01524@memverge.com
> 
> Changes in v3:
> - italicize paths
> - Link to v2: https://lore.kernel.org/r/20240315-weighted_interleave-v2-1-b742a48750b0@memverge.com
> 
> Changes in v2:
> - make flag documentation implementation-agnostic
> - Link to v1: https://lore.kernel.org/r/20240314-weighted_interleave-v1-1-ce85d64db0d4@memverge.com
> ---
>  man2/get_mempolicy.2 | 12 ++++++++++--
>  man2/mbind.2         | 18 ++++++++++++++++++
>  man2/set_mempolicy.2 | 18 ++++++++++++++++++
>  3 files changed, 46 insertions(+), 2 deletions(-)
> 
> diff --git a/man2/get_mempolicy.2 b/man2/get_mempolicy.2
> index 5248f04ba..00ce287c9 100644
> --- a/man2/get_mempolicy.2
> +++ b/man2/get_mempolicy.2
> @@ -137,7 +137,11 @@ specifies
>  but not
>  .BR MPOL_F_ADDR ,
>  and the thread's current policy is
> -.BR MPOL_INTERLEAVE ,
> +.B MPOL_INTERLEAVE
> +or
> +.B MPOL_WEIGHTED_INTERLEAVE
> +(available since Linux 6.9),

For consistency, I try to use the same phrase everywhere:

	(since Linux x.y)

But, in simple mentions, we usually don't specify when a flag was added.
That's already documented in the proper documentation of the flag.  So
here, I'd just remove that (and the comment below).

> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
>  then
>  .BR get_mempolicy ()
>  will return in the location pointed to by a non-NULL
> @@ -206,7 +210,11 @@ specified
>  but not
>  .B MPOL_F_ADDR
>  and the current thread policy is not
> -.BR MPOL_INTERLEAVE .
> +.B MPOL_INTERLEAVE
> +or

I prefer "nor".

> +.B MPOL_WEIGHTED_INTERLEAVE
> +(added in Linux 6.9).

Same here.

> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
>  Or,
>  .I flags
>  specified
> diff --git a/man2/mbind.2 b/man2/mbind.2
> index b0e961f9c..6f2449946 100644
> --- a/man2/mbind.2
> +++ b/man2/mbind.2
> @@ -105,6 +105,7 @@ argument must specify one of
>  .BR MPOL_DEFAULT ,
>  .BR MPOL_BIND ,
>  .BR MPOL_INTERLEAVE ,
> +.BR MPOL_WEIGHTED_INTERLEAVE ,
>  .BR MPOL_PREFERRED ,
>  or
>  .B MPOL_LOCAL
> @@ -243,6 +244,23 @@ at least 1\ MB or bigger with a fairly uniform access pattern.
>  Accesses to a single page of the area will still be limited to
>  the memory bandwidth of a single node.
>  .TP
> +.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758

Here is where we usually document the kernel versions.  So here (and
in set_mempolicy.2) is good, and enough, I think.

Have a lovely night!
Alex

> +This mode interleaves page allocations across the nodes specified in
> +.I nodemask
> +according to the weights in
> +.IR /sys/kernel/mm/mempolicy/weighted_interleave .
> +For example, if bits 0, 2, and 5 are raised in
> +.IR nodemask ,
> +and the contents of
> +.IR /sys/kernel/mm/mempolicy/weighted_interleave/node0 ,
> +.IR /sys/ .\|.\|. /node2 ,
> +and
> +.IR /sys/ .\|.\|. /node5
> +are 4, 7, and 9, respectively,
> +then pages in this region will be allocated on nodes 0, 2, and 5
> +in a 4:7:9 ratio.
> +.TP
>  .B MPOL_PREFERRED
>  This mode sets the preferred node for allocation.
>  The kernel will try to allocate pages from this
> diff --git a/man2/set_mempolicy.2 b/man2/set_mempolicy.2
> index fc3ad9df8..3c08b6bf0 100644
> --- a/man2/set_mempolicy.2
> +++ b/man2/set_mempolicy.2
> @@ -63,6 +63,7 @@ argument must specify one of
>  .BR MPOL_DEFAULT ,
>  .BR MPOL_BIND ,
>  .BR MPOL_INTERLEAVE ,
> +.BR MPOL_WEIGHTED_INTERLEAVE ,
>  .BR MPOL_PREFERRED ,
>  or
>  .B MPOL_LOCAL
> @@ -199,6 +200,23 @@ the memory bandwidth of a single node.
>  .\" To be effective the memory area should be fairly large,
>  .\" at least 1 MB or bigger.
>  .TP
> +.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
> +This mode interleaves page allocations across the nodes specified in
> +.I nodemask
> +according to the weights in
> +.IR /sys/kernel/mm/mempolicy/weighted_interleave .
> +For example, if bits 0, 2, and 5 are raised in
> +.IR nodemask ,
> +and the contents of
> +.IR /sys/kernel/mm/mempolicy/weighted_interleave/node0 ,
> +.IR /sys/ .\|.\|. /node2 ,
> +and
> +.IR /sys/ .\|.\|. /node5
> +are 4, 7, and 9, respectively,
> +then pages in this region will be allocated on nodes 0, 2, and 5
> +in a 4:7:9 ratio.
> +.TP
>  .B MPOL_PREFERRED
>  This mode sets the preferred node for allocation.
>  The kernel will try to allocate pages from this node first
> 
> ---
> base-commit: a4ea5f76215dcf1d8d017eb65ab12919ccf09f3f
> change-id: 20240313-weighted_interleave-e8141ed754f9
> 
> Best regards,
> -- 
> Svetly Todorov <svetly.todorov@memverge.com>
> 
> 

-- 
<https://www.alejandro-colomar.es/>
Looking for a remote C programming job at the moment.

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Re: [PATCH v5] man2: add MPOL_WEIGHTED_INTERLEAVE documentation

[Svetly Todorov]

Hi Alex,
>> index 5248f04ba..00ce287c9 100644
>> --- a/man2/get_mempolicy.2
>> +++ b/man2/get_mempolicy.2
>> @@ -137,7 +137,11 @@ specifies
>>   but not
>>   .BR MPOL_F_ADDR ,
>>   and the thread's current policy is
>> -.BR MPOL_INTERLEAVE ,
>> +.B MPOL_INTERLEAVE
>> +or
>> +.B MPOL_WEIGHTED_INTERLEAVE
>> +(available since Linux 6.9),
> For consistency, I try to use the same phrase everywhere:
>
> 	(since Linux x.y)
>
> But, in simple mentions, we usually don't specify when a flag was added.
> That's already documented in the proper documentation of the flag.  So
> here, I'd just remove that (and the comment below).
Got it. This was one of those things I was unsure of.
I think I was referencing
 > If
 > .I flags
 > specifies
 > .B MPOL_F_MEMS_ALLOWED
 > (available since Linux 2.6.24)
from earlier in the file.
>> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
>>   then
>>   .BR get_mempolicy ()
>>   will return in the location pointed to by a non-NULL
>> @@ -206,7 +210,11 @@ specified
>>   but not
>>   .B MPOL_F_ADDR
>>   and the current thread policy is not
>> -.BR MPOL_INTERLEAVE .
>> +.B MPOL_INTERLEAVE
>> +or
> I prefer "nor".
Sure, will change to neither/nor.
>> +.B MPOL_WEIGHTED_INTERLEAVE
>> +(added in Linux 6.9).
> Same here.
I'll drop this one, too.
>> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
>>   Or,
>>   .I flags
>>   specified
>> diff --git a/man2/mbind.2 b/man2/mbind.2
>> index b0e961f9c..6f2449946 100644
>> --- a/man2/mbind.2
>> +++ b/man2/mbind.2
>> @@ -105,6 +105,7 @@ argument must specify one of
>>   .BR MPOL_DEFAULT ,
>>   .BR MPOL_BIND ,
>>   .BR MPOL_INTERLEAVE ,
>> +.BR MPOL_WEIGHTED_INTERLEAVE ,
>>   .BR MPOL_PREFERRED ,
>>   or
>>   .B MPOL_LOCAL
>> @@ -243,6 +244,23 @@ at least 1\ MB or bigger with a fairly uniform access pattern.
>>   Accesses to a single page of the area will still be limited to
>>   the memory bandwidth of a single node.
>>   .TP
>> +.BR MPOL_WEIGHTED_INTERLEAVE " (since Linux 6.9)"
>> +.\" commit fa3bea4e1f8202d787709b7e3654eb0a99aed758
> Here is where we usually document the kernel versions.  So here (and
> in set_mempolicy.2) is good, and enough, I think.
>
> Have a lovely night!
> Alex
Sounds good. Yeah, get_mempolicy was getting pretty crowded with the
extra parentheticals, and the hash comments felt out of place.
I'm glad we're OK to drop them outright.


Svetly