Re: [Xen-devel] [PATCH 6/6] xl: 'xl info' print outstanding claims if enabled (claim_mode=1 in xl.conf)

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Thu, Mar 28, 2013 at 04:47:17PM +0000, Ian Jackson wrote:
> Konrad Rzeszutek Wilk writes ("[PATCH 6/6] xl: 'xl info' print outstanding 
> claims if enabled (claim_mode=1 in xl.conf)"):
> > This patch provides the value of the currently outstanding pages
> > claimed for all domains. This is a total global value that influences
> > the hypervisors' MM system.
> > 
> > When a claim call is done, a reservation for a specific amount of pages
> > is set and also a global value is incremented. This global value is then
> > reduced as the domain's memory is populated and eventually reaches zero.
> > The toolstack can also choose to set the domain's claim to zero which
> > cancels the reservation and decrements the global value by the amount
> > of claim that has not been satisfied.
> 
> This description is good, but something like it needs to be in the
> documentation.

The documentation being xl.conf right? It already is in xen.conf thanks
to the first patch.

> 
> > +uint64_t libxl_get_claiminfo(libxl_ctx *ctx)
> > +{
> > +    long l;
> > +
> > +    l = xc_domain_get_outstanding_pages(ctx->xch);
> > +    if (l < 0)
> > +        return l;
> > +
> > +    /* In MB */
> > +    return (l >> 8);
> > +}
> 
> libxl functions should return libxl error values, not whatever you got
> from libxc.

OK.
> 
> I don't mind very much what the libxc function returns but the libxl
> function needs to handle the error properly.  See Ian C's comments on
> the previous version of this patch.

OK, I probably missed something in his reply - the errno that we would
mostly get (-ENOSYS) is neutered, so that it would not pipe up to
libxl (first patch).

However, there is of course nothing stopping from adding better error
handling in this code in case we get -EPERM or such. Patch shortly coming up.

> 
> Thanks,
> Ian.

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