From mboxrd@z Thu Jan  1 00:00:00 1970
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: windows tmem
Date: Wed, 29 May 2013 11:42:11 -0400
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To: James Harper <james.harper@bendigoit.com.au>
Cc: Paul Durrant <Paul.Durrant@citrix.com>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
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On Wed, May 29, 2013 at 12:19:25AM +0000, James Harper wrote:
> > 
> > I am not familiar with the Windows APIs, but it sounds like you
> > want to use the tmem ephermeal disk cache as an secondary cache
> > (which is BTW what Linux does too).
> > 
> > That is OK the only thing you need to keep in mind that the
> > hypervisor might flush said cache out if it decides to do it
> > (say a new guest is launched and it needs the memory that
> > said cache is using).
> > 
> > So the tmem_get might tell that it does not have the page anymore.
> 
> Yes I've read the brief :)
> 
> I actually wanted to implement the equivalent of 'frontswap' originally by trapping writes to the pagefile. A bit of digging and testing suggests it may not be possible to determine when a page written to the pagefile is discarded, meaning that tmem use would just grow until fill and then stop being useful unless I eject pages on an LRU basis or something, so ephemeral tmem as a best-effort write-through cache might be the best and easiest starting point.
> 

<nods>
> James