Message-ID: <51E43F91.1040906@zytor.com>
Date: Mon, 15 Jul 2013 11:29:37 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Robin Holt <holt@sgi.com>
CC: Nathan Zimmer <nzimmer@sgi.com>, Yinghai Lu <yinghai@kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>, Rob Landley <rob@landley.net>,
        Mike Travis <travis@sgi.com>,
        Daniel J Blueman <daniel@numascale-asia.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Greg KH <gregkh@linuxfoundation.org>, Mel Gorman <mgorman@suse.de>
Subject: Re: [RFC 4/4] Sparse initialization of struct page array.
References: <1373594635-131067-1-git-send-email-holt@sgi.com> <1373594635-131067-5-git-send-email-holt@sgi.com> <CAE9FiQW1s2UwCY6OjzD3+2wG8SjCr1QyCpajhZbk_XhmnFQW4Q@mail.gmail.com> <20130715174551.GA58640@asylum.americas.sgi.com> <51E4375E.1010704@zytor.com> <20130715182615.GF3421@sgi.com>
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On 07/15/2013 11:26 AM, Robin Holt wrote:
> Is there a fairly cheap way to determine definitively that the struct
> page is not initialized?

By definition I would assume no.  The only way I can think of would be
to unmap the memory associated with the struct page in the TLB and
initialize the struct pages at trap time.

> I think this patch set can change fairly drastically if we have that.
> I think I will start working up those changes and code a heavy-handed
> check until I hear of an alternative way to cheaply check.

	-hpa


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