From: Tim Small <tim@buttersideup.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Doug Thompson <norsk5@yahoo.com>,
ncunningham-lkml@crca.org.au, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Chris Friesen <cfriesen@nortel.com>,
Pavel Machek <pavel@suse.cz>,
bluesmoke-devel@lists.sourceforge.net,
Arjan van de Ven <arjan@infradead.org>
Subject: Re: marching through all physical memory in software
Date: Fri, 30 Jan 2009 20:20:36 +0000 [thread overview]
Message-ID: <49836114.1090209@buttersideup.com> (raw)
In-Reply-To: <m1wscc7fop.fsf@fess.ebiederm.org>
Eric W. Biederman wrote:
> A background software scrubber simply has the job of rewritting memory
> to it's current content so that the data and the ecc check bits are
> guaranteed to be in sync
Don't you just need to READ memory? The memory controller hardware
takes care of the rest in the vast majority of cases.
You only need to rewrite RAM if a correctable error occurs, and the
chipset doesn't support automatic write-back of the corrected value (a
different problem altogether...). The actual memory bits themselves are
refreshed by the hardware quite frequently (max of every 64ms for DDR2,
I believe)...
Cheers,
Tim.
WARNING: multiple messages have this Message-ID (diff)
From: Tim Small <tim@buttersideup.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Doug Thompson <norsk5@yahoo.com>,
ncunningham-lkml@crca.org.au, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Chris Friesen <cfriesen@nortel.com>,
Pavel Machek <pavel@suse.cz>,
bluesmoke-devel@lists.sourceforge.net,
Arjan van de Ven <arjan@infradead.org>
Subject: Re: marching through all physical memory in software
Date: Fri, 30 Jan 2009 20:20:36 +0000 [thread overview]
Message-ID: <49836114.1090209@buttersideup.com> (raw)
In-Reply-To: <m1wscc7fop.fsf@fess.ebiederm.org>
Eric W. Biederman wrote:
> A background software scrubber simply has the job of rewritting memory
> to it's current content so that the data and the ecc check bits are
> guaranteed to be in sync
Don't you just need to READ memory? The memory controller hardware
takes care of the rest in the vast majority of cases.
You only need to rewrite RAM if a correctable error occurs, and the
chipset doesn't support automatic write-back of the corrected value (a
different problem altogether...). The actual memory bits themselves are
refreshed by the hardware quite frequently (max of every 64ms for DDR2,
I believe)...
Cheers,
Tim.
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next prev parent reply other threads:[~2009-01-30 21:03 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <715599.77204.qm@web50111.mail.re2.yahoo.com>
2009-01-30 19:32 ` marching through all physical memory in software Eric W. Biederman
2009-01-30 19:32 ` Eric W. Biederman
2009-01-30 20:20 ` Tim Small [this message]
2009-01-30 20:20 ` Tim Small
2009-01-31 3:54 ` Eric W. Biederman
2009-01-31 3:54 ` Eric W. Biederman
2009-01-31 12:48 ` Tim Small
2009-01-31 12:48 ` Tim Small
2009-01-31 13:43 ` Henrique de Moraes Holschuh
2009-01-31 13:43 ` Henrique de Moraes Holschuh
2009-01-31 21:27 ` Pavel Machek
2009-01-31 21:27 ` Pavel Machek
2009-02-01 1:25 ` Henrique de Moraes Holschuh
2009-02-01 1:25 ` Henrique de Moraes Holschuh
2009-01-30 21:10 ` Nigel Cunningham
2009-01-30 21:10 ` Nigel Cunningham
2009-02-02 18:29 ` Chris Friesen
2009-02-02 18:29 ` Chris Friesen
2009-02-02 22:45 ` Valdis.Kletnieks
2009-02-03 14:31 ` Chris Friesen
2009-02-03 14:31 ` Chris Friesen
2009-02-03 22:25 ` Pavel Machek
2009-02-03 22:25 ` Pavel Machek
2009-02-04 16:03 ` Chris Friesen
2009-02-04 16:03 ` Chris Friesen
2009-02-04 16:47 ` Dave Jiang
2009-02-04 16:47 ` Dave Jiang
2009-01-26 15:38 Chris Friesen
2009-01-26 15:59 ` Arjan van de Ven
2009-01-27 18:29 ` Chris Friesen
2009-01-27 20:16 ` Eric W. Biederman
2009-01-27 20:16 ` Eric W. Biederman
2009-01-28 19:38 ` Pavel Machek
2009-01-28 19:38 ` Pavel Machek
2009-01-30 9:05 ` Nigel Cunningham
2009-01-30 9:05 ` Nigel Cunningham
2009-01-30 9:13 ` Pavel Machek
2009-01-30 9:13 ` Pavel Machek
2009-01-30 13:00 ` Nigel Cunningham
2009-01-30 13:00 ` Nigel Cunningham
2009-02-06 9:00 ` Andi Kleen
2009-02-07 3:03 ` Henrique de Moraes Holschuh
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