Message-ID: <51C8A728.8010409@zytor.com>
Date: Mon, 24 Jun 2013 13:08:08 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Ingo Molnar <mingo@kernel.org>
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
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>
In-Reply-To: <20130624193959.GB4065@gmail.com>
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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.

	-hpa


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