Re: [Xen-devel] tmem ephemeral page discarding

[Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>]

> From: James Harper [mailto:james.harper@xxxxxxxxxxxxxxxx]
> Sent: Monday, June 03, 2013 7:42 PM
> To: Dan Magenheimer; Konrad Wilk
> Cc: xen-devel@xxxxxxxxxxxxx
> Subject: RE: [Xen-devel] tmem ephemeral page discarding
> 
> >
> > And ephemeral pages (as Konrad replied) are kept in a LRU queue across all
> > (tmem-aware) guests and the LRU ephemeral page across all guests is
> > discarded.  Or if a weight limit is exceeded, the LRU ephemeral
> > page belonging to the current guest is discarded.
> >
> 
> Yep that sounds about perfect.
> 
> I can't seem to get it working under 64 bit windows at the moment... keeps 
> returning -ENOSYS and I'm
> wondering if windows and linux differ in their structure alignment or 
> something. I remember this being
> a problem with vbd.

Any chance you've not enabled it?  Tmem is disabled by default
and you need to provide "tmem" as a boot parameter to xen to
enable it.  Tmem calls from a guest will fail if it is
disabled.

> Btw, the choice of 'new' as a struct name in the tmem struct isn't 
> necessarily wise... it might never
> come up but 'new' is a reserved word in c++.

Hmmm... Where are you seeing it?  I do see it in the tmem
code as a local parameter ("new" is used in code in other
places in Xen as well), but not in a public structure definition.

Thanks,
Dan

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