Re: Android low memory killer vs. memory pressure notifications

[Frank Rowand]

On 12/20/11 16:28, Anton Vorontsov wrote:
> On Tue, Dec 20, 2011 at 01:36:00PM -0800, David Rientjes wrote:
>> On Tue, 20 Dec 2011, Anton Vorontsov wrote:
>>
>>> Hm, assuming that metadata is no longer an issue, why do you think avoiding
>>> cgroups would be a good idea?
>>>
>>
>> It's helpful for certain end users, particularly those in the embedded 
>> world, to be able to disable as many config options as possible to reduce 
>> the size of kernel image as much as possible, so they'll want a minimal 
>> amount of kernel functionality that allows such notifications.  Keep in 
>> mind that CONFIG_CGROUP_MEM_RES_CTLR is not enabled by default because of 
>> this (enabling it, CONFIG_RESOURCE_COUNTERS, and CONFIG_CGROUPS increases 
>> the size of the kernel text by ~1%),
> 
> So for 2MB kernel that's about 20KB of an additional text... This seems
> affordable, especially as a trade-off for the things that cgroups may
> provide.

A comment from http://lkml.indiana.edu/hypermail/linux/kernel/1102.1/00412.html:

"I care about 5K. (But honestly, I don't actively hunt stuff less than
10K in size, because there's too many of them to chase, currently)."

> 
> The fact is, for desktop and server Linux, cgroups slowly becomes a
> mandatory thing. And the reason for this is that cgroups mechanism
> provides some very useful features (in an extensible way, like plugins),
> i.e. a way to manage and track processes and its resources -- which is the
> main purpose of cgroups.

And for embedded and for real-time, some of us do not want cgroups to be
a mandatory thing.  We want it to remain configurable.  My personal
interest is in keeping the latency of certain critical paths (especially
in the scheduler) short and consistent.

-Frank

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