* [PATCH] docs/vm: clarify overcommit amount sysctl behavior
@ 2021-12-11 19:41 Anssi Hannula
2021-12-11 22:21 ` Matthew Wilcox
0 siblings, 1 reply; 4+ messages in thread
From: Anssi Hannula @ 2021-12-11 19:41 UTC (permalink / raw)
To: Jonathan Corbet; +Cc: linux-doc, linux-kernel
Documentation/vm/overcommit-accounting.rst says that the overcommit
amount can be set via vm.overcommit_ratio and vm.overcommit_kbytes.
Add a clarification that those only take effect in overcommit handling
mode 2 ("Don't overcommit"), i.e. they do not act as an "additional"
limit that is always enforced.
Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
---
I've had to look this one up in the code enough times already :)
Documentation/vm/overcommit-accounting.rst | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/Documentation/vm/overcommit-accounting.rst b/Documentation/vm/overcommit-accounting.rst
index 0dd54bbe4afa..1addb0c374a4 100644
--- a/Documentation/vm/overcommit-accounting.rst
+++ b/Documentation/vm/overcommit-accounting.rst
@@ -34,7 +34,8 @@ The Linux kernel supports the following overcommit handling modes
The overcommit policy is set via the sysctl ``vm.overcommit_memory``.
The overcommit amount can be set via ``vm.overcommit_ratio`` (percentage)
-or ``vm.overcommit_kbytes`` (absolute value).
+or ``vm.overcommit_kbytes`` (absolute value). These only have an effect
+when ``vm.overcommit_memory`` is set to 2.
The current overcommit limit and amount committed are viewable in
``/proc/meminfo`` as CommitLimit and Committed_AS respectively.
--
2.31.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] docs/vm: clarify overcommit amount sysctl behavior
2021-12-11 19:41 [PATCH] docs/vm: clarify overcommit amount sysctl behavior Anssi Hannula
@ 2021-12-11 22:21 ` Matthew Wilcox
2021-12-16 11:01 ` David Hildenbrand
0 siblings, 1 reply; 4+ messages in thread
From: Matthew Wilcox @ 2021-12-11 22:21 UTC (permalink / raw)
To: Anssi Hannula; +Cc: Jonathan Corbet, linux-doc, linux-kernel, linux-mm
On Sat, Dec 11, 2021 at 09:41:59PM +0200, Anssi Hannula wrote:
> Documentation/vm/overcommit-accounting.rst says that the overcommit
> amount can be set via vm.overcommit_ratio and vm.overcommit_kbytes.
>
> Add a clarification that those only take effect in overcommit handling
> mode 2 ("Don't overcommit"), i.e. they do not act as an "additional"
> limit that is always enforced.
>
> Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
> ---
Simple and clear improvement, IMO. Cc'ing linux-mm to get more eyes on
it.
> I've had to look this one up in the code enough times already :)
>
>
> Documentation/vm/overcommit-accounting.rst | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/vm/overcommit-accounting.rst b/Documentation/vm/overcommit-accounting.rst
> index 0dd54bbe4afa..1addb0c374a4 100644
> --- a/Documentation/vm/overcommit-accounting.rst
> +++ b/Documentation/vm/overcommit-accounting.rst
> @@ -34,7 +34,8 @@ The Linux kernel supports the following overcommit handling modes
> The overcommit policy is set via the sysctl ``vm.overcommit_memory``.
>
> The overcommit amount can be set via ``vm.overcommit_ratio`` (percentage)
> -or ``vm.overcommit_kbytes`` (absolute value).
> +or ``vm.overcommit_kbytes`` (absolute value). These only have an effect
> +when ``vm.overcommit_memory`` is set to 2.
>
> The current overcommit limit and amount committed are viewable in
> ``/proc/meminfo`` as CommitLimit and Committed_AS respectively.
> --
> 2.31.1
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] docs/vm: clarify overcommit amount sysctl behavior
2021-12-11 22:21 ` Matthew Wilcox
@ 2021-12-16 11:01 ` David Hildenbrand
2021-12-16 22:53 ` Jonathan Corbet
0 siblings, 1 reply; 4+ messages in thread
From: David Hildenbrand @ 2021-12-16 11:01 UTC (permalink / raw)
To: Matthew Wilcox, Anssi Hannula
Cc: Jonathan Corbet, linux-doc, linux-kernel, linux-mm
On 11.12.21 23:21, Matthew Wilcox wrote:
> On Sat, Dec 11, 2021 at 09:41:59PM +0200, Anssi Hannula wrote:
>> Documentation/vm/overcommit-accounting.rst says that the overcommit
>> amount can be set via vm.overcommit_ratio and vm.overcommit_kbytes.
>>
>> Add a clarification that those only take effect in overcommit handling
>> mode 2 ("Don't overcommit"), i.e. they do not act as an "additional"
>> limit that is always enforced.
>>
>> Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
>> ---
>
> Simple and clear improvement, IMO. Cc'ing linux-mm to get more eyes on
> it.
As I had the same idea to just make this clearer in the context of
advanced documentation for virtio-mem, so I approve :)
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] docs/vm: clarify overcommit amount sysctl behavior
2021-12-16 11:01 ` David Hildenbrand
@ 2021-12-16 22:53 ` Jonathan Corbet
0 siblings, 0 replies; 4+ messages in thread
From: Jonathan Corbet @ 2021-12-16 22:53 UTC (permalink / raw)
To: David Hildenbrand, Matthew Wilcox, Anssi Hannula
Cc: linux-doc, linux-kernel, linux-mm
David Hildenbrand <david@redhat.com> writes:
> On 11.12.21 23:21, Matthew Wilcox wrote:
>> On Sat, Dec 11, 2021 at 09:41:59PM +0200, Anssi Hannula wrote:
>>> Documentation/vm/overcommit-accounting.rst says that the overcommit
>>> amount can be set via vm.overcommit_ratio and vm.overcommit_kbytes.
>>>
>>> Add a clarification that those only take effect in overcommit handling
>>> mode 2 ("Don't overcommit"), i.e. they do not act as an "additional"
>>> limit that is always enforced.
>>>
>>> Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
>>> ---
>>
>> Simple and clear improvement, IMO. Cc'ing linux-mm to get more eyes on
>> it.
>
> As I had the same idea to just make this clearer in the context of
> advanced documentation for virtio-mem, so I approve :)
>
> Reviewed-by: David Hildenbrand <david@redhat.com>
Applied, thanks.
jon
^ permalink raw reply [flat|nested] 4+ messages in thread
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2021-12-11 19:41 [PATCH] docs/vm: clarify overcommit amount sysctl behavior Anssi Hannula
2021-12-11 22:21 ` Matthew Wilcox
2021-12-16 11:01 ` David Hildenbrand
2021-12-16 22:53 ` Jonathan Corbet
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