Re: [libvirt] [PATCH] Update docs for memory parameters and memtune command

On Mon, 18 Oct 2010 09:55:46 +0200, Matthias Bolte <matthias.bolte(a)googlemail.com&gt; wrote: > 2010/10/18 Nikunj A. Dadhania <nikunj(a)linux.vnet.ibm.com&gt;: > > From: Nikunj A. Dadhania <nikunj(a)linux.vnet.ibm.com&gt; > > > > docs/formatdomain.html.in: Add memtune element details [...] > > @@ -211,6 +216,22 @@ > >         <code>hugepages</code> element set within it. This tells the > >         hypervisor that the guest should have its memory allocated using > >         hugepages instead of the normal native page size.</dd> > > +      <dt><code>memtune</code></dt> > > +      <dd> The optional <code>memtune</code> element provides details > > +      regarding the memory tuneable parameters for the domain. If this is > > +      omitted, it defaults to the OS provided defaults.</dd> > > +      <dt><code>hard_limit</code></dt> > > +      <dd> The optional <code>hard_limit</code> element is the maximum memory > > +       the guest can use. The units for this value are kilobytes (i.e. blocks > > +       of 1024 bytes)</dd> > > Well, the maximum of memory a guest can use is also controlled by the > memory and currentMemory element in some way. How does hard_limit > relate to those two? > memory and currentMemory are related to balloon size, while these are operating system provided limits. > > +      <dt><code>soft_limit</code></dt> > > +      <dd> The optional <code>soft_limit</code> element is the memory limit to > > +       enforce during memory contention. The units for this value are > > +       kilobytes (i.e. blocks of 1024 bytes)</dd> > > Is this an upper or a lower limit? Does it mean in case of contention > this guest may only use up to soft_limit kilobytes of memory (upper > limit)? Or does it mean in case of contention make sure that this > guest can access at least soft_limit kilobytes of memory (lower > limit)? > Upper limit of memory the guest can use(i.e upto soft_limit) during contention. Balbir, correct me if this isn't correct.

> How does this relate to the memory and currentMemory element? > At present no relation, they are implemented by the OS.

> How does it related to the min_guarantee element? > It is not related to min_guarantee. > > +      <dt><code>swap_hard_limit</code></dt> > > +      <dd> The optional <code>swap_hard_limit</code> element is the maximum > > +       swap the guest can use. The units for this value are kilobytes > > +       (i.e. blocks of 1024 bytes)</dd> > > What about the min_guarantee element anyway? It's not implemented in virsh. > Missed it, I will add the docs about min_gaurantee and send the updated patch. It is not implemented in virsh. However, I have taken care of parsing them in domain configuration.