linux-kernel - Re: TREE_SRCU slows hotplug by factor ~16

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Message-Id: <20170424033250.GX3956@linux.vnet.ibm.com>
Date:   Sun, 23 Apr 2017 20:32:50 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     Mike Galbraith <efault@....de>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: TREE_SRCU slows hotplug by factor ~16

On Mon, Apr 24, 2017 at 04:48:09AM +0200, Mike Galbraith wrote:
> Greetings,
> 
> Running Steven's hotplug stress script in tip w. CLASSIC_SRCU takes 55s
> in my i4790 box, whereas TREE_SRCU takes over 16m.  (Master with the
> same config does it in 39s.. but then lockdep isn't enabled in master)

That doesn't sound good...

But exactly which version are you using?  There were some 8x slowdowns
earlier this week that have since been fixed.  Also, how many CPUs are
on your system?

							Thanx, Paul