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From:   Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: Re: [PATCH 4/5] Powerpc/hw-breakpoint: Optimize disable path
To:     Michael Neuling <mikey@neuling.org>
Cc:     mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        npiggin@gmail.com, christophe.leroy@c-s.fr,
        naveen.n.rao@linux.vnet.ibm.com,
        Ravi Bangoria <ravi.bangoria@linux.ibm.com>
References: <20190618042732.5582-1-ravi.bangoria@linux.ibm.com>
 <20190618042732.5582-5-ravi.bangoria@linux.ibm.com>
 <ab7e5fac2a1ea78181900f5df7411b1f51b65eb9.camel@neuling.org>
Date:   Wed, 19 Jun 2019 11:32:28 +0530
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On 6/18/19 11:45 AM, Michael Neuling wrote:
> On Tue, 2019-06-18 at 09:57 +0530, Ravi Bangoria wrote:
>> Directly setting dawr and dawrx with 0 should be enough to
>> disable watchpoint. No need to reset individual bits in
>> variable and then set in hw.
> 
> This seems like a pointless optimisation to me. 
> 
> I'm all for adding more code/complexity if it buys us some performance, but I
> can't imagine this is a fast path (nor have you stated any performance
> benefits). 

This gets called from sched_switch. I expected the improvement when
we switch from monitored process to non-monitored process. With such
scenario, I tried to measure the difference in execution time of
set_dawr but I don't see any improvement. So I'll drop the patch.