Re: [gentoo-user] Re: htop wants cgroups

[Daniel Campbell]

On 05/01/2017 08:01 AM, Jorge Almeida wrote:
> On Mon, May 1, 2017 at 2:46 PM, Rich Freeman <rich0@g.o> wrote:
>> On Sun, Apr 30, 2017 at 4:17 PM, Kai Krakow <hurikhan77@×××××.com> wrote:
>>> Am Sun, 30 Apr 2017 10:33:05 -0700
>>> schrieb Jorge Almeida <jjalmeida@×××××.com>:
>>>
>>>> It makes sense that the kernel has it. Should it be enabled? For a
>>>> server, probably. For a single-user workstation? Maybe.
>>>
>
>>
>> Honestly, I can't think of why you wouldn't want to use it.
>>
>> The use cases of killing orphan processes and managing resources at a
>> service level have already been mentioned.
>
> I don't usually have orphan processes (that process 1 doesn't reap).
> My services don't require fine tuning re resources.
>
>>
>> Another use case is that the kernel automatically takes cgroups into
>> account when scheduling.  So, if one of your services launches a bunch
>> of children they'll be weighted together when allocating CPU.  That
>> means that a service with ten threads won't get 10x the CPU of a
>> service with one thread if CPU becomes limiting, assuming equal
>> niceness/etc.  On a multi-user system the same would apply to the user
>> running 100 processes vs 1.
>>
>> I also use cgroups to monitor memory use/etc at a service level.
>
>  I don't have complex services (some might argue that very complex
> services are badly designed services, but I leave that discussion to
> pros). I only run single-user workstations.
>
>>
>> Sure, they're somewhat optional, but they're a pretty useful kernel feature.
>
> No arguing there. Still, it shouldn't be pushed. It's a bad sign.
>
> Jorge
>
cgroups are not being pushed in this case. Portage threw up a warning,
letting you know that some features of htop may not be available without
the CONFIG_CGROUPS flag on in the kernel. htop should work to your
liking as it is right now. Go try it out!

I'm having a little trouble understanding why this particular package
has you worried when there are dozens of others that spit out similar
"heads up" warnings, like qemu, anything relating to graphics and
virtualization... they're helpful messages that let you know that, if
something doesn't work as you expect, it's probably due to something you
have disabled. That's it.

Perfect example: I use an AMD processor, but still get 'warning'
messages about checking CONFIG_KVM_INTEL and other variables. qemu still
works, because my kernel is built to virtualize with my CPU. Someone
with an Intel CPU might really want that warning message, though.

I've not dabbled in cgroups but they seem very useful to those who need
to manage processes in ways the kernel itself can enforce. Cgroups
merely help htop do its job.
-- 
Daniel Campbell - Gentoo Developer
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