Date: Mon, 14 Aug 2017 16:29:00 +0900
From: Byungchul Park <byungchul.park@lge.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <max.byungchul.park@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        tglx@linutronix.de, Michel Lespinasse <walken@google.com>,
        kirill@shutemov.name,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org,
        npiggin@gmail.com, kernel-team@lge.com
Subject: Re: [PATCH v8 06/14] lockdep: Detect and handle hist_lock ring
 buffer overwrite
Message-ID: <20170814072900.GL20323@X58A-UD3R>
References: <20170810115922.kegrfeg6xz7mgpj4@tardis>
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 <20170811080329.3ehu7pp7lcm62ji6@tardis>
 <20170811085201.GI20323@X58A-UD3R>
 <20170811094448.GJ20323@X58A-UD3R>
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On Mon, Aug 14, 2017 at 03:05:22PM +0800, Boqun Feng wrote:
> > 1. Boqun's approach
> 
> My approach requires(additionally):
> 
> 	MAX_XHLOCKS_NR * sizeof(unsigned int) // because of the hist_id field in hist_lock
> 
> bytes per task.
> 
> > 2. Peterz's approach
> 
> And Peter's approach requires(additionally):
> 
> 	1 * sizeof(unsigned int)
> 
> bytes per task.
> 
> So basically we need some tradeoff between memory footprints and history
> precision here.

I see what you intended. Then, Peterz's one looks better.