Date: Tue, 25 Jun 2013 09:31:22 +0200
From: Ingo Molnar <mingo@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Nathan Zimmer <nzimmer@sgi.com>, holt@sgi.com, travis@sgi.com,
        rob@landley.net, tglx@linutronix.de, mingo@redhat.com,
        yinghai@kernel.org, akpm@linux-foundation.org,
        gregkh@linuxfoundation.org, x86@kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [RFC 2/2] x86_64, mm: Reinsert the absent memory
Message-ID: <20130625073122.GB11420@gmail.com>
References: <1371831934-156971-1-git-send-email-nzimmer@sgi.com>
 <1371831934-156971-3-git-send-email-nzimmer@sgi.com>
 <20130623092840.GB13445@gmail.com>
 <20130623093250.GA13776@gmail.com>
 <51C88400.7090907@zytor.com>
 <20130624193959.GB4065@gmail.com>
 <51C8A728.8010409@zytor.com>
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* H. Peter Anvin <hpa@zytor.com> wrote:

> On 06/24/2013 12:39 PM, Ingo Molnar wrote:
> > 
> > That might be a bit too granular: if we hit such an uninitialized block of 
> > memory we'd have to process 262,144 pages - potentially from an IRQ 
> > handler that does GFP_ATOMIC... or other latency critical code.
> > 
> > With 2MB we'd have to on-demand initialize 512 pages, which shouldn't show 
> > up during normal use.
> > 
> 
> No... you split the gigabyte page into 511 2M pages and 512 4K pages.

Oh, double deferred initialization. That should solve the 32 exabyte 
problem as well I guess ;-)

Thanks,

	Ingo
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