Re: [resend][PATCH 2/4] Revert "oom: deprecate oom_adj tunable"

[David Rientjes]

On Tue, 23 Nov 2010, KOSAKI Motohiro wrote:

> > > No irrelevant. Your patch break their environment even though
> > > they don't use oom_adj explicitly. because their application are using it.
> > > 
> > 
> > The _only_ difference too oom_adj since the rewrite is that it is now 
> > mapped on a linear scale rather than an exponential scale.  
> 
> _only_ mean don't ZERO different. Why do userland application need to rewrite?
> 

Because NOTHING breaks with the new mapping.  Eight months later since 
this was initially proposed on linux-mm, you still cannot show a single 
example that depended on the exponential mapping of oom_adj.  I'm not 
going to continue responding to your criticism about this point since your 
argument is completely and utterly baseless.

> Again, IF you need to [0 .. 1000] range, you can calculate it by your
> application. current oom score can be get from /proc/pid/oom_score and
> total memory can be get from /proc/meminfo. You shouldn't have break
> anything.
> 

That would require the userspace tunable to be adjusted anytime a task's 
mempolicy changes, its nodemask changes, it's cpuset attachment changes, 
its mems change, a memcg limit changes, etc.  The only constant is the 
task's priority, and the current oom_score_adj implementation preserves 
that unless explicitly changed later by the user.  I completely understand 
that you may not have a use for this.
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