Re: Memory overcommit

From: Vedran FuraÄ
Date: Mon Nov 02 2009 - 14:56:53 EST

David Rientjes wrote:

> On Fri, 30 Oct 2009, Vedran Furac wrote:
>> Well, you are kernel hacker, not me. You know how linux mm works much
>> more than I do. I just reported a, what I think is a big problem, which
>> needs to be solved ASAP (2.6.33).
> The oom killer heuristics have not been changed recently, why is this
> suddenly a problem that needs to be immediately addressed? The heuristics
> you've been referring to have been used for at least three years.

It isn't "suddenly a problem", but only a problem, big long time
problem. If it is three years old, then it should have been addressed
asap three years ago (and we would not need to talk about it now,

> However, I don't think we can simply change the baseline (like the rss
> change which has been added to -mm (??)) and consider it a major
> improvement when it severely impacts how system administrators are able to
> tune the badness heuristic from userspace via /proc/pid/oom_adj. I'm sure
> you'd agree that user input is important in this matter and so that we
> should maximize that ability rather than make it more difficult. That's
> my main criticism of the suggestions thus far (and, sorry, but I have to
> look out for production server interests here: you can't take away our
> ability to influence oom badness scoring just because other simple
> heuristics may be more understandable).
> What would be better, and what I think we'll end up with, is a root
> selectable heuristic so that production servers and desktop machines can
> use different heuristics to make oom kill selections. We already have
> /proc/sys/vm/oom_kill_allocating_task which I added 1-2 years ago to
> address concerns specifically of SGI and their enormously long tasklist
> scans. This would be variation on that idea and would include different
> simplistic behaviors (such as always killing the most memory hogging task,
> killing the most recently started task by the same uid, etc), and leave
> the default heuristic much the same as currently.

OK, agreed. Did you take a look at the set of patches Kame sent today?


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