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[Xen-devel] RE: Ballooning up

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] RE: Ballooning up
From: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Date: Mon, 13 Sep 2010 14:39:14 -0700 (PDT)
Cc: Konrad Wilk <konrad.wilk@xxxxxxxxxx>, Daniel Kiper <dkiper@xxxxxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
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Also, looking at the latest code in xen/next-2.6.32, I see
you have removed the balloon lock.  Isn't this necessary
to ensure multiple vcpus aren't racing on adjusting the
balloon size (and performing the hypercalls to do it)?
IOW, are increase/decrease_reservation and the calls
into the hypervisor thread-safe?

And, related especially if the lock goes away (repeat
of question asked here
http://lists.xensource.com/archives/html/xen-devel/2010-08/msg01664.html )
wouldn't it be better to use a separate workqueue rather than
the kernel default queue, and is there any reason to
queue the work on every cpu rather than just one?


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