Date: Wed, 10 Jun 2015 20:27:10 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
cc: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: RFC: futex_wait() can DoS the tick
In-Reply-To: <1433953758.6306.25.camel@gmail.com>
Message-ID: <alpine.DEB.2.11.1506102024380.3786@nanos>
References: <1433940278.6814.66.camel@gmail.com>  <alpine.DEB.2.11.1506101639230.3786@nanos> <1433953758.6306.25.camel@gmail.com>
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On Wed, 10 Jun 2015, Mike Galbraith wrote:
> Virgin source or kernels with zillion+ patches, doesn't matter.  To test
> virgin source earlier than EFI_STUB I had to pollute the source with
> EFI backports, but nothing else.
> 
> Just a sec while I check yet again that absolutely virgin master really
> really does stall....  Yup.  I pinned the tescase to CPU3..
> 
> LOC:       7432       5803       5418       6387       3371       3039       5757       3080   Local timer interrupts <== here
> LOC:       7560       6028       5632       6394       3538       3195       5937       3084   Local timer interrupts
> LOC:       7747       6135       5720       6394       3543       3262       6087       3086   Local timer interrupts
> LOC:       7930       6206       5785       6394       3571       3288       6303       3087   Local timer interrupts

So now it would be helpful to have a trace to see what CPU3 is
actually doing.

Thanks,

	tglx
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