LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Matt Mackall <mpm@selenic.com>
To: Dave Hansen <haveblue@us.ibm.com>
Cc: Hans Rosenfeld <hans.rosenfeld@amd.com>,
	linux-kernel@vger.kernel.org, Adam Litke <aglitke@gmail.com>,
	nacc <nacc@linux.vnet.ibm.com>,
	Jon Tollefson <kniht@linux.vnet.ibm.com>,
	Adam Litke <agl@linux.vnet.ibm.com>
Subject: Re: [RFC][PATCH] make /proc/pid/pagemap work with huge pages and return page size
Date: Fri, 29 Feb 2008 16:46:12 -0600	[thread overview]
Message-ID: <1204325172.4175.31.camel@cinder.waste.org> (raw)
In-Reply-To: <1204324234.2086.14.camel@nimitz.home.sr71.net>


On Fri, 2008-02-29 at 14:30 -0800, Dave Hansen wrote:
> On Thu, 2008-02-28 at 17:15 -0800, Matt Mackall wrote:
> > > The only issue is that this is *after* the code has decided that a
> > > particular virtual area is for huge pages.  The best arch-generic
> > > interface I know for that is: is_vm_hugetlb_page(), but that is
> > > VMA-based.  Perhaps we should change the pagemap walk to pass the VMA
> > > around. 
> > 
> > I'd rather avoid that. Requiring a VMA to poke at these things shouldn't
> > -really- be necessary.
> 
> Yeah, this is strictly true.  But, it also assumes that we have all of
> the data about where large pages are based on the contents of the
> pagetables alone.  It's possible that we can derive this, or code up a
> bunch of arch-specific functions to do this, but it certainly doesn't
> exist today.  I'm just not keen on going and learning about how each and
> every architecture encodes hugetlb information in their pagetables. :(
> 
> The fact is that we treat pagetables in hugetlb areas completely
> differently than normal pages.  All of the generic functions that deal
> with pagetables magically punt over to the hugetlb code when they see a
> hugetlb VMA.
> 
> I think although it isn't strictly necessary, it is going to save a ton
> of work to just pass the VMAs around.

Well in any case, step 1 should be to finalize the interface. Let's
start with a single patch that does nothing but move the exported bits
around and makes room for the page shift bits. Are we agreed on what
that should look like now?

ps: my laptop died on Tuesday, so I'll be struggling to even read email
until its replacement arrives.

-- 
Mathematics is the supreme nostalgia of our time.


  reply	other threads:[~2008-02-29 22:47 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-20 13:57 Hans Rosenfeld
2008-02-23  2:18 ` Matt Mackall
2008-02-23 18:31   ` Dave Hansen
2008-02-25 12:09     ` Hans Rosenfeld
2008-02-25 18:39       ` Dave Hansen
2008-02-26 20:25         ` Hans Rosenfeld
2008-02-27 17:44           ` Dave Hansen
2008-02-28 12:00             ` Hans Rosenfeld
2008-02-29  0:49               ` Dave Hansen
2008-02-29  1:15                 ` Matt Mackall
2008-02-29 22:30                   ` Dave Hansen
2008-02-29 22:46                     ` Matt Mackall [this message]
2008-03-05 16:00                       ` Hans Rosenfeld
2008-03-05 16:32                         ` Dave Hansen
2008-03-05 17:22                           ` Hans Rosenfeld
2008-02-23  8:06 ` Andrew Morton
2008-02-23 15:25   ` Matt Mackall

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1204325172.4175.31.camel@cinder.waste.org \
    --to=mpm@selenic.com \
    --cc=agl@linux.vnet.ibm.com \
    --cc=aglitke@gmail.com \
    --cc=hans.rosenfeld@amd.com \
    --cc=haveblue@us.ibm.com \
    --cc=kniht@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=nacc@linux.vnet.ibm.com \
    --subject='Re: [RFC][PATCH] make /proc/pid/pagemap work with huge pages and return page size' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).