Date: Tue, 17 Jun 2014 17:15:17 -0700
From: Andi Kleen <ak@linux.intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: paulmck@linux.vnet.ibm.com, LKML <linux-kernel@vger.kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        "Chen, Tim C" <tim.c.chen@intel.com>, Christoph Lameter <cl@linux.com>
Subject: Re: [bisected] pre-3.16 regression on open() scalability
Message-ID: <20140618001517.GL8178@tassilo.jf.intel.com>
References: <539B594C.8070004@intel.com>
 <20140613224519.GV4581@linux.vnet.ibm.com>
 <53A0CAE5.9000702@intel.com>
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> It also ends up eating a new cacheline in a bunch of pretty hot paths.
> It would be nice to be able to keep the fast path part of this as at
> least read-only.
> 
> Could we do something (functionally) like the attached patch?  Instead
> of counting cond_resched() calls, we could just specify some future time
> by which we want have a quiescent state.  We could even push the time to
> be something _just_ before we would have declared a stall.

I still think it's totally the wrong place. cond_resched() is in so
many fast paths (every lock, every allocation). It just doesn't
make sense to add non essential things like this to it.

I would be rather to just revert the original patch.

-Andi
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