[PATCH] new cgroup controller "fork"
Alan Cox
alan at lxorguk.ukuu.org.uk
Thu Nov 3 19:03:30 UTC 2011
> Putting a reasonable limit on jobs that are expected to run only for a
> limited amount of time, with a limited amount of total resources. For
fork is an almost irrelevant resource. Address space (ie memory), file
handles and the like are actual constrained resources.
I can't help thinking this is focussing on a completely irrelevant
cornercase issue. It belongs as part of a general resource limiting
cgroup that also deals with memory, I/O and the like. In fact most of
these resources are a balancing act.
Who cares if you have 10,000 threads. We can handle that without trying.
10,000 different mappings is a whole different ball game, and 100,000 file
handles in some configurations might also matter.
In short in your specific environment a fork runaway is a symptom you can
use to detect and sometimes halt the failure case. It's not the actual
resource problem and it doesn't solve the general case.
> Similar existing feature: RLIMIT_CPU. Millions of users have it in
> their kernels, but nobody uses it nowadays. And it's not even
> optional.
It's required by the standards, and basically unmeasurable overhead.
> Btw. I have no problem with maintaining this patch (and a whole bunch
> of others) in my proprietary git repository at work forever. They're
> very useful for my employer. I'm just trying to be a good citizen by
> sharing them.
Sure - I'm just not seeing that a whole separate cgroup for it is
appropriate or a good plan. Anyone doing real resource management needs
the rest of the stuff anyway.
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