linux-kernel - Re: [PATCH v7 00/23] locking/lockdep: Add support for dynamic keys

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Date:   Fri, 22 Feb 2019 23:13:14 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Bart Van Assche <bvanassche@....org>
Cc:     mingo@...hat.com, will.deacon@....com, tj@...nel.org,
        longman@...hat.com, johannes.berg@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 00/23] locking/lockdep: Add support for dynamic keys

On Fri, Feb 22, 2019 at 09:20:34AM -0800, Bart Van Assche wrote:
> On 2/22/19 8:26 AM, Peter Zijlstra wrote:
> > I've gone over all and I think it looks ok now; I'll give it another
> > round tomorrow^Wmonday and then queue bits.
> > 
> > So far the only changes I've made are the below. I'm not entirely sure
> > on the unconditional validity check on DEBUG_LOCKDEP, maybe I'll add a
> > boot param for that.
> 
> Hi Peter,
> 
> Please keep in mind that calling check_data_structures() slows down the
> kernel a lot and also that it makes systems much less responsive. This is
> because the consistency checks disable interrupts for a long time, up to
> several seconds. That is why I think it should be possible to enable and
> disable the consistency checks independent of other kernel config options.

Ah, yes. So I had expected expensive, but hadn't tried it yet.

I'll make it a boot option.