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* [PATCH] Documentation: incorrect formula to calculate CommitLimit value
@ 2014-05-22 12:04 Petr Oros
  2014-05-22 20:20 ` Randy Dunlap
  0 siblings, 1 reply; 2+ messages in thread
From: Petr Oros @ 2014-05-22 12:04 UTC (permalink / raw)
  To: rdunlap; +Cc: linux-kernel, linux-doc, trivial

The formula to calculate "CommitLimit" value mentioned in kernel documentation is incorrect.
Right formula is: CommitLimit = ([total RAM pages] - [total huge TLB pages]) * overcommit_ratio / 100 + [total swap pages]

Signed-off-by: Petr Oros <poros@redhat.com>
---
 Documentation/filesystems/proc.txt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 8b9cd8e..b58d764 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -854,7 +854,8 @@ WritebackTmp: Memory used by FUSE for temporary writeback buffers
               if strict overcommit accounting is enabled (mode 2 in
               'vm.overcommit_memory').
               The CommitLimit is calculated with the following formula:
-              CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
+              CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
+                             overcommit_ratio / 100 + [total swap pages]
               For example, on a system with 1G of physical RAM and 7G
               of swap with a `vm.overcommit_ratio` of 30 it would
               yield a CommitLimit of 7.3G.
-- 
1.9.0



^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] Documentation: incorrect formula to calculate CommitLimit value
  2014-05-22 12:04 [PATCH] Documentation: incorrect formula to calculate CommitLimit value Petr Oros
@ 2014-05-22 20:20 ` Randy Dunlap
  0 siblings, 0 replies; 2+ messages in thread
From: Randy Dunlap @ 2014-05-22 20:20 UTC (permalink / raw)
  To: poros; +Cc: linux-kernel, linux-doc, trivial

On 05/22/2014 05:04 AM, Petr Oros wrote:
> The formula to calculate "CommitLimit" value mentioned in kernel documentation is incorrect.
> Right formula is: CommitLimit = ([total RAM pages] - [total huge TLB pages]) * overcommit_ratio / 100 + [total swap pages]
> 
> Signed-off-by: Petr Oros <poros@redhat.com>

Acked-by: Randy Dunlap <rdunlap@infradead.org>

Jiri, please grab this patch.

Thanks.


> ---
>  Documentation/filesystems/proc.txt | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
> index 8b9cd8e..b58d764 100644
> --- a/Documentation/filesystems/proc.txt
> +++ b/Documentation/filesystems/proc.txt
> @@ -854,7 +854,8 @@ WritebackTmp: Memory used by FUSE for temporary writeback buffers
>                if strict overcommit accounting is enabled (mode 2 in
>                'vm.overcommit_memory').
>                The CommitLimit is calculated with the following formula:
> -              CommitLimit = ('vm.overcommit_ratio' * Physical RAM) + Swap
> +              CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
> +                             overcommit_ratio / 100 + [total swap pages]
>                For example, on a system with 1G of physical RAM and 7G
>                of swap with a `vm.overcommit_ratio` of 30 it would
>                yield a CommitLimit of 7.3G.
> 


-- 
~Randy

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2014-05-22 12:04 [PATCH] Documentation: incorrect formula to calculate CommitLimit value Petr Oros
2014-05-22 20:20 ` Randy Dunlap

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