[libvirt] [PATCH] virsh: fix memtune's help message for swap_hard_limit
KAMEZAWA Hiroyuki
kamezawa.hiroyu at jp.fujitsu.com
Wed Mar 16 00:39:26 UTC 2011
On Tue, 15 Mar 2011 14:30:02 +0000
"Daniel P. Berrange" <berrange at redhat.com> wrote:
> On Mon, Mar 14, 2011 at 09:24:58PM -0600, Eric Blake wrote:
> > On 03/09/2011 01:13 AM, KAMEZAWA Hiroyuki wrote:
> > > +++ b/docs/schemas/domain.rng
> > > @@ -341,7 +341,7 @@
> > > </optional>
> > > <!-- Maximum swap area the VM can use -->
> > > <optional>
> > > - <element name="swap_hard_limit">
> > > + <element name="memswap_hard_limit">
> > > <ref name="memoryKB"/>
> > > </element>
> > > </optional>
> >
> > This needs fixing. We need to support both old and new styles, since
> > we've had a release that used the old name. That means we need to add a
> > new test, rather than modifying an existing test, to show that we can
> > parse both styles when reading XML, but that we generate the new style
> > when writing.
>
> Adding back-compat hacks are only reasonable if we have already had
> an accident & mistakenly changed public facing XML/API. Given, that
> we're not in that situation, we should simply not make the proposed
> changes to the XML/API, rather than changing it & adding compat hacks.
>
> >
> > Maybe danpb or DV will have some further comments on whether it is wise
> > to deprecate XML like this; it's unpleasant business to think about
> > backwards compatibility. We might be stuck with just documenting that
> > the choice of name was unfortunate to avoid the hassle of back-compat;
> > but I hope it doesn't come to that.
>
>
> > > diff --git a/tools/virsh.c b/tools/virsh.c
> > > index 14c6d6b..b790248 100644
> > > --- a/tools/virsh.c
> > > +++ b/tools/virsh.c
> > > @@ -3034,8 +3034,8 @@ static const vshCmdOptDef opts_memtune[] = {
> > > N_("Max memory in kilobytes")},
> > > {"soft-limit", VSH_OT_INT, VSH_OFLAG_NONE,
> > > N_("Memory during contention in kilobytes")},
> > > - {"swap-hard-limit", VSH_OT_INT, VSH_OFLAG_NONE,
> > > - N_("Max swap in kilobytes")},
> > > + {"memswap-hard-limit", VSH_OT_INT, VSH_OFLAG_NONE,
> > > + N_("Max memory+swap in kilobytes")},
> >
> > This name change might break existing clients of virsh. Is there any
> > way to support the older name? Maybe we need to add some more framework
> > into virsh option parsing to allow option aliases that the parser
> > recognizes but which don't get documented, so that someone still doing
> > --swap-hard-limit will work?
>
> Agreed, we shouldn't change this either.
>
> > I guess I need more convincing that this rename is worth the hassle, or
> > whether we are stuck with the smaller but less controversial patch of
> > documenting that the name isn't optimal for what it really represents.
>
> Agreed, we should simply improve docs for the existing names to clarify
> their meaning.
>
Ok, I'll stop.
-Kame
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