Re: [PATCH 9/15] Mempolicy: Use MPOL_PREFERRED for system-wide default policy

Re: [PATCH 9/15] Mempolicy: Use MPOL_PREFERRED for system-wide default policy

[Randy Dunlap]

On Fri, 04 Apr 2008 11:00:40 -0400 Lee Schermerhorn wrote:

> PATCH 09/15 Mempolicy:  Use MPOL_PREFERRED for system-wide default policy
> 
> Against:  2.6.25-rc8-mm1
> 
> Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
> 
>  Documentation/vm/numa_memory_policy.txt |   52 ++++++++----------------
>  mm/mempolicy.c                          |   68 +++++++++++++++++++-------------
>  2 files changed, 59 insertions(+), 61 deletions(-)
> 
> Index: linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt
> ===================================================================
> --- linux-2.6.25-rc8-mm1.orig/Documentation/vm/numa_memory_policy.txt	2008-04-02 17:47:26.000000000 -0400
> +++ linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt	2008-04-02 17:47:37.000000000 -0400

> @@ -187,19 +170,18 @@ Components of Memory Policies
>  
>  	MPOL_PREFERRED:  This mode specifies that the allocation should be
>  	attempted from the single node specified in the policy.  If that
> -	allocation fails, the kernel will search other nodes, exactly as
> -	it would for a local allocation that started at the preferred node
> -	in increasing distance from the preferred node.  "Local" allocation
> -	policy can be viewed as a Preferred policy that starts at the node
> +	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.

Something in the patch lines above seems to be foobarred.
I.e., the sentences/lines don't flow correctly.

>  	    Internally, the Preferred policy uses a single node--the


---
~Randy

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Re: [PATCH 8/15] Mempolicy: Rework mempolicy Reference Counting [yet again]

[Randy Dunlap]

On Fri, 04 Apr 2008 11:00:34 -0400 Lee Schermerhorn wrote:

> PATCH 08/15 Mem Policy:  rework mempolicy reference counting [yet again]
> 
> Against:  2.6.25-rc8-mm1
> 
>  Documentation/vm/numa_memory_policy.txt |   68 ++++++++++++++
> 
> Index: linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt
> ===================================================================
> --- linux-2.6.25-rc8-mm1.orig/Documentation/vm/numa_memory_policy.txt	2008-04-02 17:47:15.000000000 -0400
> +++ linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt	2008-04-02 17:47:26.000000000 -0400
> @@ -311,6 +311,74 @@ Components of Memory Policies
>  	    MPOL_PREFERRED policies that were created with an empty nodemask
>  	    (local allocation).

...

> +   Because of this extra reference counting, and because we must lookup
> +   shared policies in a tree structure under spinlock, shared policies are
> +   more expensive to use in the page allocation path.  This is expecially

                                                                  especially

> +   true for shared policies on shared memory regions shared by tasks running
> +   on different NUMA nodes.  This extra overhead can be avoided by always
> +   falling back to task or system default policy for shared memory regions,
> +   or by prefaulting the entire shared memory region into memory and locking
> +   it down.  However, this might not be appropriate for all applications.
> +
>  MEMORY POLICY APIs
>  
>  Linux supports 3 system calls for controlling memory policy.  These APIS


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~Randy

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Re: [PATCH 9/15] Mempolicy: Use MPOL_PREFERRED for system-wide default policy

[Lee Schermerhorn]

On Mon, 2008-04-14 at 10:23 -0700, Randy Dunlap wrote:
> On Fri, 04 Apr 2008 11:00:40 -0400 Lee Schermerhorn wrote:
> 
> > PATCH 09/15 Mempolicy:  Use MPOL_PREFERRED for system-wide default policy
> > 
> > Against:  2.6.25-rc8-mm1
> > 
> > Signed-off-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
> > 
> >  Documentation/vm/numa_memory_policy.txt |   52 ++++++++----------------
> >  mm/mempolicy.c                          |   68 +++++++++++++++++++-------------
> >  2 files changed, 59 insertions(+), 61 deletions(-)
> > 
> > Index: linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt
> > ===================================================================
> > --- linux-2.6.25-rc8-mm1.orig/Documentation/vm/numa_memory_policy.txt	2008-04-02 17:47:26.000000000 -0400
> > +++ linux-2.6.25-rc8-mm1/Documentation/vm/numa_memory_policy.txt	2008-04-02 17:47:37.000000000 -0400
> 
> > @@ -187,19 +170,18 @@ Components of Memory Policies
> >  
> >  	MPOL_PREFERRED:  This mode specifies that the allocation should be
> >  	attempted from the single node specified in the policy.  If that
> > -	allocation fails, the kernel will search other nodes, exactly as
> > -	it would for a local allocation that started at the preferred node
> > -	in increasing distance from the preferred node.  "Local" allocation
> > -	policy can be viewed as a Preferred policy that starts at the node
> > +	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.
> 
> Something in the patch lines above seems to be foobarred.
> I.e., the sentences/lines don't flow correctly.

Looks like I forgot to delete the line starting with 'containing ...'.
I'll fix it, along with the 'expecially' in patch 8. [That's not a word,
huh? :)]

Lee

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