From: "Luck, Tony" <tony.luck@intel.com>
To: Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com>,
LinuxIA64 <linux-ia64@vger.kernel.org>
Cc: linux-mm <linux-mm@kvack.org>
Subject: RE: [RFC/PATCH] pfn_valid() more generic : intro[0/2]
Date: Tue, 5 Oct 2004 23:33:28 -0700 [thread overview]
Message-ID: <B8E391BBE9FE384DAA4C5C003888BE6F0221CC82@scsmsx401.amr.corp.intel.com> (raw)
>ia64's ia64_pfn_valid() uses get_user() for checking whether a
>page struct is available or not. I think this is an irregular
>implementation and following patches
>are a more generic replacement, careful_pfn_valid(). It uses 2
>level table.
It is odd ... but a somewhat convenient way to make check whether
the page struct exists, while handling the fault if it is in an
area of virtual mem_map that doesn't exist. I think that in practice
we rarely call it with a pfn that generates a fault (except in error
paths).
How big will the pfn_validmap[] be for a very sparse physical space
like SGI Altix? I'm not sure I see how PFN_VALID_MAPSHIFT is
generated for each system.
Why do we need a loop when looking in the 2nd level? Can't the
entry from the 1st level point us to the right place?
-Tony
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next reply other threads:[~2004-10-06 6:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-06 6:33 Luck, Tony [this message]
2004-10-06 7:33 ` Hiroyuki KAMEZAWA
-- strict thread matches above, loose matches on Subject: below --
2004-10-06 6:20 Hiroyuki KAMEZAWA
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