* Re: [PATCH 1/1] doc, mempolicy: Fix wrong document in numa_memory_policy.txt
@ 2014-04-10 23:23 ` Randy Dunlap
0 siblings, 0 replies; 10+ messages in thread
From: Randy Dunlap @ 2014-04-10 23:23 UTC (permalink / raw)
To: Tang Chen, hannes, mhocko, bsingharora, kamezawa.hiroyu
Cc: cgroups, linux-mm, linux-doc, linux-kernel, guz.fnst,
Andrew Morton
On 04/01/2014 08:53 PM, Tang Chen wrote:
> In document numa_memory_policy.txt, the following examples for flag
> MPOL_F_RELATIVE_NODES are incorrect.
>
> For example, consider a task that is attached to a cpuset with
> mems 2-5 that sets an Interleave policy over the same set with
> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
> interleave now occurs over nodes 3,5-6. If the cpuset's mems
> then change to 0,2-3,5, then the interleave occurs over nodes
> 0,3,5.
>
> According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
> the nodemasks the user specifies should be considered relative to the
> current task's mems_allowed.
> (https://lkml.org/lkml/2008/2/29/428)
>
> And according to numa_memory_policy.txt, if the user's nodemask includes
> nodes that are outside the range of the new set of allowed nodes, then
> the remap wraps around to the beginning of the nodemask and, if not already
> set, sets the node in the mempolicy nodemask.
>
> So in the example, if the user specifies 2-5, for a task whose mems_allowed
> is 3-7, the nodemasks should be remapped the third, fourth, fifth, sixth
> node in mems_allowed. like the following:
>
> mems_allowed: 3 4 5 6 7
>
> relative index: 0 1 2 3 4
> 5
>
> So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
>
> And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
> remapped to 0,2-3,5, but not 0,3,5.
>
> mems_allowed: 0 2 3 5
>
> relative index: 0 1 2 3
> 4 5
>
>
> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Wow. This was not an April fools joke, right?
Have there been any acks of this? I haven't seen any responses to it.
Andrew, do you want to merge it?
> ---
> Documentation/vm/numa_memory_policy.txt | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt
> index 4e7da65..badb050 100644
> --- a/Documentation/vm/numa_memory_policy.txt
> +++ b/Documentation/vm/numa_memory_policy.txt
> @@ -174,7 +174,6 @@ Components of Memory Policies
> allocation fails, the kernel will search other nodes, in order of
> increasing distance from the preferred node based on information
> provided by the platform firmware.
> - containing the cpu where the allocation takes place.
>
> Internally, the Preferred policy uses a single node--the
> preferred_node member of struct mempolicy. When the internal
> @@ -275,9 +274,9 @@ Components of Memory Policies
> For example, consider a task that is attached to a cpuset with
> mems 2-5 that sets an Interleave policy over the same set with
> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
> - interleave now occurs over nodes 3,5-6. If the cpuset's mems
> + interleave now occurs over nodes 3,5-7. If the cpuset's mems
> then change to 0,2-3,5, then the interleave occurs over nodes
> - 0,3,5.
> + 0,2-3,5.
>
> Thanks to the consistent remapping, applications preparing
> nodemasks to specify memory policies using this flag should
>
--
~Randy
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/1] doc, mempolicy: Fix wrong document in numa_memory_policy.txt
@ 2014-04-10 23:23 ` Randy Dunlap
0 siblings, 0 replies; 10+ messages in thread
From: Randy Dunlap @ 2014-04-10 23:23 UTC (permalink / raw)
To: Tang Chen, hannes, mhocko, bsingharora, kamezawa.hiroyu
Cc: cgroups, linux-mm, linux-doc, linux-kernel, guz.fnst,
Andrew Morton
On 04/01/2014 08:53 PM, Tang Chen wrote:
> In document numa_memory_policy.txt, the following examples for flag
> MPOL_F_RELATIVE_NODES are incorrect.
>
> For example, consider a task that is attached to a cpuset with
> mems 2-5 that sets an Interleave policy over the same set with
> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
> interleave now occurs over nodes 3,5-6. If the cpuset's mems
> then change to 0,2-3,5, then the interleave occurs over nodes
> 0,3,5.
>
> According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
> the nodemasks the user specifies should be considered relative to the
> current task's mems_allowed.
> (https://lkml.org/lkml/2008/2/29/428)
>
> And according to numa_memory_policy.txt, if the user's nodemask includes
> nodes that are outside the range of the new set of allowed nodes, then
> the remap wraps around to the beginning of the nodemask and, if not already
> set, sets the node in the mempolicy nodemask.
>
> So in the example, if the user specifies 2-5, for a task whose mems_allowed
> is 3-7, the nodemasks should be remapped the third, fourth, fifth, sixth
> node in mems_allowed. like the following:
>
> mems_allowed: 3 4 5 6 7
>
> relative index: 0 1 2 3 4
> 5
>
> So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
>
> And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
> remapped to 0,2-3,5, but not 0,3,5.
>
> mems_allowed: 0 2 3 5
>
> relative index: 0 1 2 3
> 4 5
>
>
> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Wow. This was not an April fools joke, right?
Have there been any acks of this? I haven't seen any responses to it.
Andrew, do you want to merge it?
> ---
> Documentation/vm/numa_memory_policy.txt | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt
> index 4e7da65..badb050 100644
> --- a/Documentation/vm/numa_memory_policy.txt
> +++ b/Documentation/vm/numa_memory_policy.txt
> @@ -174,7 +174,6 @@ Components of Memory Policies
> allocation fails, the kernel will search other nodes, in order of
> increasing distance from the preferred node based on information
> provided by the platform firmware.
> - containing the cpu where the allocation takes place.
>
> Internally, the Preferred policy uses a single node--the
> preferred_node member of struct mempolicy. When the internal
> @@ -275,9 +274,9 @@ Components of Memory Policies
> For example, consider a task that is attached to a cpuset with
> mems 2-5 that sets an Interleave policy over the same set with
> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
> - interleave now occurs over nodes 3,5-6. If the cpuset's mems
> + interleave now occurs over nodes 3,5-7. If the cpuset's mems
> then change to 0,2-3,5, then the interleave occurs over nodes
> - 0,3,5.
> + 0,2-3,5.
>
> Thanks to the consistent remapping, applications preparing
> nodemasks to specify memory policies using this flag should
>
--
~Randy
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/1] doc, mempolicy: Fix wrong document in numa_memory_policy.txt
2014-04-10 23:23 ` Randy Dunlap
@ 2014-04-11 8:13 ` Tang Chen
-1 siblings, 0 replies; 10+ messages in thread
From: Tang Chen @ 2014-04-11 8:13 UTC (permalink / raw)
To: Randy Dunlap
Cc: hannes, mhocko, bsingharora, kamezawa.hiroyu, cgroups, linux-mm,
linux-doc, linux-kernel, guz.fnst, Andrew Morton
Hi Randy,
On 04/11/2014 07:23 AM, Randy Dunlap wrote:
> On 04/01/2014 08:53 PM, Tang Chen wrote:
>> In document numa_memory_policy.txt, the following examples for flag
>> MPOL_F_RELATIVE_NODES are incorrect.
>>
>> For example, consider a task that is attached to a cpuset with
>> mems 2-5 that sets an Interleave policy over the same set with
>> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
>> interleave now occurs over nodes 3,5-6. If the cpuset's mems
>> then change to 0,2-3,5, then the interleave occurs over nodes
>> 0,3,5.
>>
>> According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
>> the nodemasks the user specifies should be considered relative to the
>> current task's mems_allowed.
>> (https://lkml.org/lkml/2008/2/29/428)
>>
>> And according to numa_memory_policy.txt, if the user's nodemask includes
>> nodes that are outside the range of the new set of allowed nodes, then
>> the remap wraps around to the beginning of the nodemask and, if not already
>> set, sets the node in the mempolicy nodemask.
>>
>> So in the example, if the user specifies 2-5, for a task whose mems_allowed
>> is 3-7, the nodemasks should be remapped the third, fourth, fifth, sixth
>> node in mems_allowed. like the following:
>>
>> mems_allowed: 3 4 5 6 7
>>
>> relative index: 0 1 2 3 4
>> 5
>>
>> So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
>>
>> And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
>> remapped to 0,2-3,5, but not 0,3,5.
>>
>> mems_allowed: 0 2 3 5
>>
>> relative index: 0 1 2 3
>> 4 5
>>
>>
>> Signed-off-by: Tang Chen<tangchen@cn.fujitsu.com>
>
> Wow. This was not an April fools joke, right?
>
> Have there been any acks of this? I haven't seen any responses to it.
Thanks for the reply. I found this problem when I was reading the doc.
I think it is wrong. And according to the original patch:
https://lkml.org/lkml/2008/2/29/428
I think it should be fixed in the above way. But if I was wrong, please
let me know, and I think we can at least improve the doc since it is
not that easy to understand.
Thanks. :)
>
> Andrew, do you want to merge it?
>
>
>> ---
>> Documentation/vm/numa_memory_policy.txt | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt
>> index 4e7da65..badb050 100644
>> --- a/Documentation/vm/numa_memory_policy.txt
>> +++ b/Documentation/vm/numa_memory_policy.txt
>> @@ -174,7 +174,6 @@ Components of Memory Policies
>> allocation fails, the kernel will search other nodes, in order of
>> increasing distance from the preferred node based on information
>> provided by the platform firmware.
>> - containing the cpu where the allocation takes place.
>>
>> Internally, the Preferred policy uses a single node--the
>> preferred_node member of struct mempolicy. When the internal
>> @@ -275,9 +274,9 @@ Components of Memory Policies
>> For example, consider a task that is attached to a cpuset with
>> mems 2-5 that sets an Interleave policy over the same set with
>> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
>> - interleave now occurs over nodes 3,5-6. If the cpuset's mems
>> + interleave now occurs over nodes 3,5-7. If the cpuset's mems
>> then change to 0,2-3,5, then the interleave occurs over nodes
>> - 0,3,5.
>> + 0,2-3,5.
>>
>> Thanks to the consistent remapping, applications preparing
>> nodemasks to specify memory policies using this flag should
>>
>
>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/1] doc, mempolicy: Fix wrong document in numa_memory_policy.txt
@ 2014-04-11 8:13 ` Tang Chen
0 siblings, 0 replies; 10+ messages in thread
From: Tang Chen @ 2014-04-11 8:13 UTC (permalink / raw)
To: Randy Dunlap
Cc: hannes, mhocko, bsingharora, kamezawa.hiroyu, cgroups, linux-mm,
linux-doc, linux-kernel, guz.fnst, Andrew Morton
Hi Randy,
On 04/11/2014 07:23 AM, Randy Dunlap wrote:
> On 04/01/2014 08:53 PM, Tang Chen wrote:
>> In document numa_memory_policy.txt, the following examples for flag
>> MPOL_F_RELATIVE_NODES are incorrect.
>>
>> For example, consider a task that is attached to a cpuset with
>> mems 2-5 that sets an Interleave policy over the same set with
>> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
>> interleave now occurs over nodes 3,5-6. If the cpuset's mems
>> then change to 0,2-3,5, then the interleave occurs over nodes
>> 0,3,5.
>>
>> According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
>> the nodemasks the user specifies should be considered relative to the
>> current task's mems_allowed.
>> (https://lkml.org/lkml/2008/2/29/428)
>>
>> And according to numa_memory_policy.txt, if the user's nodemask includes
>> nodes that are outside the range of the new set of allowed nodes, then
>> the remap wraps around to the beginning of the nodemask and, if not already
>> set, sets the node in the mempolicy nodemask.
>>
>> So in the example, if the user specifies 2-5, for a task whose mems_allowed
>> is 3-7, the nodemasks should be remapped the third, fourth, fifth, sixth
>> node in mems_allowed. like the following:
>>
>> mems_allowed: 3 4 5 6 7
>>
>> relative index: 0 1 2 3 4
>> 5
>>
>> So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
>>
>> And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
>> remapped to 0,2-3,5, but not 0,3,5.
>>
>> mems_allowed: 0 2 3 5
>>
>> relative index: 0 1 2 3
>> 4 5
>>
>>
>> Signed-off-by: Tang Chen<tangchen@cn.fujitsu.com>
>
> Wow. This was not an April fools joke, right?
>
> Have there been any acks of this? I haven't seen any responses to it.
Thanks for the reply. I found this problem when I was reading the doc.
I think it is wrong. And according to the original patch:
https://lkml.org/lkml/2008/2/29/428
I think it should be fixed in the above way. But if I was wrong, please
let me know, and I think we can at least improve the doc since it is
not that easy to understand.
Thanks. :)
>
> Andrew, do you want to merge it?
>
>
>> ---
>> Documentation/vm/numa_memory_policy.txt | 5 ++---
>> 1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/vm/numa_memory_policy.txt b/Documentation/vm/numa_memory_policy.txt
>> index 4e7da65..badb050 100644
>> --- a/Documentation/vm/numa_memory_policy.txt
>> +++ b/Documentation/vm/numa_memory_policy.txt
>> @@ -174,7 +174,6 @@ Components of Memory Policies
>> allocation fails, the kernel will search other nodes, in order of
>> increasing distance from the preferred node based on information
>> provided by the platform firmware.
>> - containing the cpu where the allocation takes place.
>>
>> Internally, the Preferred policy uses a single node--the
>> preferred_node member of struct mempolicy. When the internal
>> @@ -275,9 +274,9 @@ Components of Memory Policies
>> For example, consider a task that is attached to a cpuset with
>> mems 2-5 that sets an Interleave policy over the same set with
>> MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
>> - interleave now occurs over nodes 3,5-6. If the cpuset's mems
>> + interleave now occurs over nodes 3,5-7. If the cpuset's mems
>> then change to 0,2-3,5, then the interleave occurs over nodes
>> - 0,3,5.
>> + 0,2-3,5.
>>
>> Thanks to the consistent remapping, applications preparing
>> nodemasks to specify memory policies using this flag should
>>
>
>
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/1] doc, mempolicy: Fix wrong document in numa_memory_policy.txt
2014-04-10 23:23 ` Randy Dunlap
@ 2014-04-11 10:54 ` David Rientjes
-1 siblings, 0 replies; 10+ messages in thread
From: David Rientjes @ 2014-04-11 10:54 UTC (permalink / raw)
To: Randy Dunlap
Cc: Tang Chen, hannes, mhocko, bsingharora, kamezawa.hiroyu, cgroups,
linux-mm, linux-doc, linux-kernel, guz.fnst, Andrew Morton
On Thu, 10 Apr 2014, Randy Dunlap wrote:
> On 04/01/2014 08:53 PM, Tang Chen wrote:
> > In document numa_memory_policy.txt, the following examples for flag
> > MPOL_F_RELATIVE_NODES are incorrect.
> >
> > For example, consider a task that is attached to a cpuset with
> > mems 2-5 that sets an Interleave policy over the same set with
> > MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
> > interleave now occurs over nodes 3,5-6. If the cpuset's mems
> > then change to 0,2-3,5, then the interleave occurs over nodes
> > 0,3,5.
> >
> > According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
> > the nodemasks the user specifies should be considered relative to the
> > current task's mems_allowed.
> > (https://lkml.org/lkml/2008/2/29/428)
> >
> > And according to numa_memory_policy.txt, if the user's nodemask includes
> > nodes that are outside the range of the new set of allowed nodes, then
> > the remap wraps around to the beginning of the nodemask and, if not already
> > set, sets the node in the mempolicy nodemask.
> >
> > So in the example, if the user specifies 2-5, for a task whose mems_allowed
> > is 3-7, the nodemasks should be remapped the third, fourth, fifth, sixth
> > node in mems_allowed. like the following:
> >
> > mems_allowed: 3 4 5 6 7
> >
> > relative index: 0 1 2 3 4
> > 5
> >
> > So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
> >
> > And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
> > remapped to 0,2-3,5, but not 0,3,5.
> >
> > mems_allowed: 0 2 3 5
> >
> > relative index: 0 1 2 3
> > 4 5
> >
> >
> > Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
>
> Wow. This was not an April fools joke, right?
>
It would have been a horrible joke if it was intended to be :)
> Have there been any acks of this? I haven't seen any responses to it.
>
Because everybody in the phonebook was cc'd on it except for the author
who wrote it.
Tang, good catch.
Acked-by: David Rientjes <rientjes@google.com>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/1] doc, mempolicy: Fix wrong document in numa_memory_policy.txt
@ 2014-04-11 10:54 ` David Rientjes
0 siblings, 0 replies; 10+ messages in thread
From: David Rientjes @ 2014-04-11 10:54 UTC (permalink / raw)
To: Randy Dunlap
Cc: Tang Chen, hannes, mhocko, bsingharora, kamezawa.hiroyu, cgroups,
linux-mm, linux-doc, linux-kernel, guz.fnst, Andrew Morton
On Thu, 10 Apr 2014, Randy Dunlap wrote:
> On 04/01/2014 08:53 PM, Tang Chen wrote:
> > In document numa_memory_policy.txt, the following examples for flag
> > MPOL_F_RELATIVE_NODES are incorrect.
> >
> > For example, consider a task that is attached to a cpuset with
> > mems 2-5 that sets an Interleave policy over the same set with
> > MPOL_F_RELATIVE_NODES. If the cpuset's mems change to 3-7, the
> > interleave now occurs over nodes 3,5-6. If the cpuset's mems
> > then change to 0,2-3,5, then the interleave occurs over nodes
> > 0,3,5.
> >
> > According to the comment of the patch adding flag MPOL_F_RELATIVE_NODES,
> > the nodemasks the user specifies should be considered relative to the
> > current task's mems_allowed.
> > (https://lkml.org/lkml/2008/2/29/428)
> >
> > And according to numa_memory_policy.txt, if the user's nodemask includes
> > nodes that are outside the range of the new set of allowed nodes, then
> > the remap wraps around to the beginning of the nodemask and, if not already
> > set, sets the node in the mempolicy nodemask.
> >
> > So in the example, if the user specifies 2-5, for a task whose mems_allowed
> > is 3-7, the nodemasks should be remapped the third, fourth, fifth, sixth
> > node in mems_allowed. like the following:
> >
> > mems_allowed: 3 4 5 6 7
> >
> > relative index: 0 1 2 3 4
> > 5
> >
> > So the nodemasks should be remapped to 3,5-7, but not 3,5-6.
> >
> > And for a task whose mems_allowed is 0,2-3,5, the nodemasks should be
> > remapped to 0,2-3,5, but not 0,3,5.
> >
> > mems_allowed: 0 2 3 5
> >
> > relative index: 0 1 2 3
> > 4 5
> >
> >
> > Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
>
> Wow. This was not an April fools joke, right?
>
It would have been a horrible joke if it was intended to be :)
> Have there been any acks of this? I haven't seen any responses to it.
>
Because everybody in the phonebook was cc'd on it except for the author
who wrote it.
Tang, good catch.
Acked-by: David Rientjes <rientjes@google.com>
^ permalink raw reply [flat|nested] 10+ messages in thread