linux-kernel - RE: [RFC 00/21] Generic show

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Date:	Wed, 2 Apr 2008 14:53:45 -0700
From:	"Luck, Tony" <tony.luck@...el.com>
To:	"Johannes Weiner" <hannes@...urebad.de>,
	<linux-kernel@...r.kernel.org>
Cc:	<linux-mm@...ck.org>, <mingo@...e.hu>, <davem@...emloft.net>,
	<hskinnemoen@...el.com>, <cooloney@...nel.org>, <starvik@...s.com>,
	<dhowells@...hat.com>, <ysato@...rs.sf.net>,
	<takata@...ux-m32r.org>, <geert@...ux-m68k.org>,
	<ralf@...ux-mips.org>, <kyle@...isc-linux.org>, <paulus@...ba.org>,
	<schwidefsky@...ibm.com>, <lethal@...ux-sh.org>,
	<jdike@...toit.com>, <miles@....org>, <chris@...kel.net>,
	<rmk@....linux.org.uk>
Subject: RE: [RFC 00/21] Generic show_mem()

> Tony, as far as I understand, ia64 jumps holes in the memory map with
> vmemmap_find_next_valid_pfn().  Any idea if and how this could be
> built into the generic show_mem() version?

Perhaps it might be worth looking at this when ia64 slims down to
just one memory model (using sparse virtual mem map).  But I don't
think anyone is actively working on this.  Right now we have two
very different show_mem() functions for the contig and discontig
cases.

This whole function sends shivers down my spine for a large
system though ... that inner loop looks at every single page
structure ... on a multi-terabyte machine that could run to
billions of cache misses.  Hope the users aren't in a hurry
to see the answer ... or doing something painful like:

	# watch -n 1 cat /proc/meminfo

-Tony
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