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Subject: Re: balance storm
From: Mike Galbraith <umgwanakikbuti@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Libo Chen <libo.chen@huawei.com>, tglx@linutronix.de, mingo@elte.hu,
        LKML <linux-kernel@vger.kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>, Li Zefan <lizefan@huawei.com>
Date: Tue, 27 May 2014 12:05:33 +0200
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On Tue, 2014-05-27 at 11:48 +0200, Peter Zijlstra wrote:

> So I suppose this is due to the select_idle_sibling() nonsense again,
> where we assumes L3 is a fair compromise between cheap enough and
> effective enough.

Nodz.

> Of course, Intel keeps growing the cpu count covered by L3 to ridiculous
> sizes, 8 cores isn't nowhere near their top silly, which shifts the
> balance, and there's always going to be pathological cases (like the
> proposed workload) where its just always going to suck eggs.

Test is as pathological as it gets.  15 core + SMT wouldn't be pretty.

-Mike