From: "Luck, Tony" <tony.luck@intel.com>
To: "Martin J. Bligh" <mbligh@aracnet.com>,
Hiroyuki KAMEZAWA <kamezawa.hiroyu@jp.fujitsu.com>
Cc: LinuxIA64 <linux-ia64@vger.kernel.org>, linux-mm <linux-mm@kvack.org>
Subject: RE: [RFC/PATCH] pfn_valid() more generic : arch independent part[0/2]
Date: Thu, 7 Oct 2004 08:53:32 -0700 [thread overview]
Message-ID: <B8E391BBE9FE384DAA4C5C003888BE6F022668D0@scsmsx401.amr.corp.intel.com> (raw)
>The normal way to fix the above is just to have a bitmap array
>to test - in your case a 1GB granularity would be sufficicent. That
>takes < 1 word to implement for the example above ;-)
In the general case you need a bit for each granule (since that is the
unit that the kernel admits/denies the existence of memory). But the
really sparse systems end up with a large bitmap. SGI Altix uses 49
physical address bits, and a granule size of 16MB ... so we need 2^25
bits ... i.e. 4MBbytes. While that's a drop in the ocean on a 4TB
machine, it still seems a pointless waste.
-Tony
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"aart@kvack.org"> aart@kvack.org </a>
next reply other threads:[~2004-10-07 15:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-07 15:53 Luck, Tony [this message]
2004-10-07 16:02 ` Martin J. Bligh
-- strict thread matches above, loose matches on Subject: below --
2004-10-07 5:22 Luck, Tony
2004-10-07 6:28 ` Hiroyuki KAMEZAWA
2004-10-07 14:38 ` Martin J. Bligh
2004-10-07 23:38 ` Hiroyuki KAMEZAWA
2004-10-06 6:37 Hiroyuki KAMEZAWA
2004-10-06 15:14 ` Martin J. Bligh
2004-10-07 0:10 ` Hiroyuki KAMEZAWA
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=B8E391BBE9FE384DAA4C5C003888BE6F022668D0@scsmsx401.amr.corp.intel.com \
--to=tony.luck@intel.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-ia64@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mbligh@aracnet.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox