linux-kernel - Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20110610180807.GB28500@srcf.ucam.org>
Date:	Fri, 10 Jun 2011 19:08:07 +0100
From:	Matthew Garrett <mjg59@...f.ucam.org>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	Kyungmin Park <kmpark@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ankita Garg <ankita@...ibm.com>,
	linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	svaidy@...ux.vnet.ibm.com, thomas.abraham@...aro.org
Subject: Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory
 Power Management

On Fri, Jun 10, 2011 at 10:52:48AM -0700, Paul E. McKenney wrote:
> On Fri, Jun 10, 2011 at 06:23:07PM +0100, Matthew Garrett wrote:
> > I haven't seen too many ARM servers with 256GB of RAM :) I'm mostly 
> > looking at this from an x86 perspective.
> 
> But I have seen ARM embedded systems with CPU power consumption in
> the milliwatt range, which greatly reduces the amount of RAM required
> to get significant power savings from this approach.  Three orders
> of magnitude less CPU power consumption translates (roughly) to three
> orders of magnitude less memory required -- and embedded devices with
> more than 256MB of memory are quite common.

I'm not saying that powering down memory isn't a win, just that in the 
server market we're not even getting unused memory into self refresh at 
the moment. If we can gain that hardware capability then sub-node zoning 
means that we can look at allocating (and migrating?) RAM in such a way 
as to get a lot of the win that we'd gain from actually cutting the 
power, without the added overhead of actually shrinking our working set.

-- 
Matthew Garrett | mjg59@...f.ucam.org
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/