Re: [PATCH 10 of 16] stop useless vm trashing while we wait the TIF_MEMDIE task to exit

[Andrea Arcangeli <andrea@suse.de>]

On Mon, Jun 11, 2007 at 10:56:56AM -0700, Christoph Lameter wrote:
> On Mon, 11 Jun 2007, Andrea Arcangeli wrote:
> 
> > Did you measure it or this is just your imagination? I don't buy your
> > hypothetical "several hours spent in oom_kill.c" numbers. How long
> > does "ls /proc" takes? Can your run top at all?
> 
> These are customer reports. 4 hours one and another 2 hours. I can 

How long does "ls /proc" take? Can you run top at all on such a
system (I mean before it reaches the oom point, then it'll hang for
those 4 hours with the mainline kernel, I know this and that's why I
worked to fix it and posted 18 patches so far about it).

> certainly get more reports if I ask them for more details. I will get this 
> on your SUSE radar.

If it takes 4 hours for the function out_of_memory to return, please
report it. If instead as I start to suspect, you're going to show me
the function out_of_memory called one million times and taking a few
seconds for each invocation, please test all my fixes before
reporting, there's a reason I made those changes...

Back to the local-oom: if out_of_memory takes a couple of seconds at
most as I expect (it'll be the same order of ls /proc, actually ls
/proc will be a lot slower), killing the current task in the local-oom
as a performance optimization remains a very dubious argument.

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