Re: [patch -mm 08/18] oom: badness heuristic rewrite

[David Rientjes <rientjes@google.com>]

On Thu, 3 Jun 2010, KAMEZAWA Hiroyuki wrote:

> > > > I'm glad you asked that because some recent conversation has been 
> > > > slightly confusing to me about how this affects the desktop; this rewrite 
> > > > significantly improves the oom killer's response for desktop users.  The 
> > > > core ideas were developed in the thread from this mailing list back in 
> > > > February called "Improving OOM killer" at 
> > > > http://marc.info/?t=126506191200004&r=4&w=2 -- users constantly report 
> > > > that vital system tasks such as kdeinit are killed whenever a memory 
> > > > hogging task is forked either intentionally or unintentionally.  I argued 
> > > > for a while that KDE should be taking proper precautions by adjusting its 
> > > > own oom_adj score and that of its forked children as it's an inherited 
> > > > value, but I was eventually convinced that an overall improvement to the 
> > > > heuristic must be made to kill a task that was known to free a large 
> > > > amount of memory that is resident in RAM and that we have a consistent way 
> > > > of defining oom priorities when a task is run uncontained and when it is a 
> > > > member of a memcg or cpuset (or even mempolicy now), even in the case when 
> > > > it's contained out from under the task's knowledge.  When faced with 
> > > > memory pressure from an out of control or memory hogging task on the 
> > > > desktop, the oom killer now kills it instead of a vital task such as an X 
> > > > server (and oracle, webserver, etc on server platforms) because of the use 
> > > > of the task's rss instead of total_vm statistic.
> > > 
> > > The above story teach us oom-killer need some improvement. but it haven't
> > > prove your patches are correct solution. that's why you got to ask testing way.
> > > 
> > 
> > I would consider what I said above, "when faced with memory pressure from 
> > an out of control or memory hogging task on the desktop, the oom killer 
> > now kills it instead of a vital task such as an X server because of the 
> > use of the task's rss instead of total_vm statistic" as an improvement 
> > over killing X in those cases which it currently does.  How do you 
> > disagree?
> > 
> 
> It was you who disagree using RSS for oom killing in the last winter.
> By what observation did you change your mind ? (Don't take this as criticism.
> I'm just curious.) 
> 

The fact that when I ran the new heuristic it improved the oom killer on 
my desktop to save KDE and kill a memory-hogging task that stressed it.  I 
became supportive of the idea through the discussion that went on 
specifically about using total_vm as a baseline and was convinced that it 
was better to use rss as well as a more powerful user interface so that 
admins could more accurately set their oom kill priorities even when their 
cpuset, memcg, or mempolicy placement was changed out from under it.

> My stand point:
> I don't like the new interface at all but welcome the concept for using RSS .

Using rss is not a new interface.

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