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From: Chris Friesen <cfriesen@nortel.com>
To: Dan Malek <dan@embeddededge.com>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>,
	Arjan van de Ven <arjan@infradead.org>,
	Linux Kernel list <linux-kernel@vger.kernel.org>,
	linuxppc64-dev <linuxppc64-dev@ozlabs.org>
Subject: Re: question on symbol exports
Date: Tue, 08 Feb 2005 09:36:20 -0600	[thread overview]
Message-ID: <4208DC74.4000107@nortel.com> (raw)
In-Reply-To: <bc4f2e60770528d4934b5a2e69285002@embeddededge.com>

Dan Malek wrote:
> 
> On Feb 7, 2005, at 4:35 PM, Benjamin Herrenschmidt wrote:
> 
>> Interesting... more than no swap, you must also make sure you have no
>> r/w mmap'ed file (which are technically equivalent to swap).
> 
> 
> Yeah, I kinda had a similar thought.  Just because you aren't
> swapping doesn't mean the VM subsystem isn't looking at dirty bits,
> too.  It could potentially steal a page that it thinks can be replaced
> from either a zero-fill or reading again from persistent storage.

In our existing case, the app also mlock()s the pages in question.  This 
should get around these two possible sources of inaccuracy.

Chris

WARNING: multiple messages have this Message-ID (diff)
From: Chris Friesen <cfriesen@nortel.com>
To: Dan Malek <dan@embeddededge.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	linuxppc64-dev <linuxppc64-dev@ozlabs.org>,
	Arjan van de Ven <arjan@infradead.org>,
	linuxppc-dev list <linuxppc-dev@ozlabs.org>,
	Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: question on symbol exports
Date: Tue, 08 Feb 2005 09:36:20 -0600	[thread overview]
Message-ID: <4208DC74.4000107@nortel.com> (raw)
In-Reply-To: <bc4f2e60770528d4934b5a2e69285002@embeddededge.com>

Dan Malek wrote:
> 
> On Feb 7, 2005, at 4:35 PM, Benjamin Herrenschmidt wrote:
> 
>> Interesting... more than no swap, you must also make sure you have no
>> r/w mmap'ed file (which are technically equivalent to swap).
> 
> 
> Yeah, I kinda had a similar thought.  Just because you aren't
> swapping doesn't mean the VM subsystem isn't looking at dirty bits,
> too.  It could potentially steal a page that it thinks can be replaced
> from either a zero-fill or reading again from persistent storage.

In our existing case, the app also mlock()s the pages in question.  This 
should get around these two possible sources of inaccuracy.

Chris

  reply	other threads:[~2005-02-08 15:36 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-02-01  0:15 question on symbol exports Chris Friesen
2005-02-01  7:36 ` Arjan van de Ven
2005-02-01 15:37   ` Chris Friesen
2005-02-01 15:50     ` Arjan van de Ven
2005-02-01 17:00       ` Chris Friesen
     [not found]       ` <20050204203050.GA5889@dmt.cnet>
2005-02-04 20:14         ` Chris Friesen
2005-02-04 20:14           ` Chris Friesen
2005-02-05  9:19           ` Benjamin Herrenschmidt
2005-02-05  9:19             ` Benjamin Herrenschmidt
2005-02-07 14:44             ` Chris Friesen
2005-02-07 14:44               ` Chris Friesen
2005-02-07 21:35               ` Benjamin Herrenschmidt
2005-02-07 21:35                 ` Benjamin Herrenschmidt
2005-02-07 23:02                 ` Chris Friesen
2005-02-07 23:02                   ` Chris Friesen
2005-02-07 23:42                 ` Dan Malek
2005-02-07 23:42                   ` Dan Malek
2005-02-08 15:36                   ` Chris Friesen [this message]
2005-02-08 15:36                     ` Chris Friesen

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