Re: [Xen-devel] [PATCH v8 6/6] tools: enable Cache QoS Monitoring feature for libxl/libxc

["Xu, Dongxiao" <dongxiao.xu@xxxxxxxxx>]

> -----Original Message-----
> From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
> Sent: Monday, February 10, 2014 6:16 PM
> To: Xu, Dongxiao
> Cc: xen-devel@xxxxxxxxxxxxx; keir@xxxxxxx; JBeulich@xxxxxxxx;
> Ian.Jackson@xxxxxxxxxxxxx; stefano.stabellini@xxxxxxxxxxxxx;
> andrew.cooper3@xxxxxxxxxx; konrad.wilk@xxxxxxxxxx; dgdegra@xxxxxxxxxxxxx
> Subject: Re: [PATCH v8 6/6] tools: enable Cache QoS Monitoring feature for
> libxl/libxc
> 
> On Sat, 2014-02-08 at 13:07 +0800, Dongxiao Xu wrote:
> > Introduced two new xl commands to attach/detach CQM service for a guest
> > $ xl pqos-attach cqm domid
> > $ xl pqos-detach cqm domid
> >
> > Introduce one new xl command to retrive guest CQM information
> 
> "retrieve"

Thanks.

> 
> > $ xl pqos-list cqm
> 
> Please patch the xl manpages to describe all these new commands.

OK.

> 
> I wonder though -- are these aimed at end users or are they really for
> developer use? I'm wondering if they should be exposed this way or
> whether they should be exposed by some lower level tool (similar to how
> xenpm is separate). I don't know what the correct answer is here.

I think one target should be the sys admins, who needs to watch the system 
cache usages and determine how to balance the resource.

> 
> > +int xc_domain_getcqminfo(xc_interface *xch, xc_cqminfo_t *info)
> > +{
> > +    int ret = 0;
> > +    DECLARE_SYSCTL;
> > +
> > +    sysctl.cmd = XEN_SYSCTL_getcqminfo;
> > +    if ( xc_sysctl(xch, &sysctl) < 0 )
> > +        ret = -1;
> 
> xc_sysctl returns -1 on error AFAICT. So:
>       ret = xc_sysctl(...);
>       if (ret >= 0)
>       {
>               info->etc
>       }
>       return ret;

OK.

> 
> > diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> > index 649ce50..43c0f48 100644
> > --- a/tools/libxl/libxl_types.idl
> > +++ b/tools/libxl/libxl_types.idl
> > @@ -596,3 +596,10 @@ libxl_event = Struct("event",[
> >                                   ])),
> >             ("domain_create_console_available", Struct(None, [])),
> >             ]))])
> > +
> > +libxl_cqminfo = Struct("cqminfo", [
> 
> You need to also patch libxl.h to add a suitable LIBXL_HAVE_FOO define,
> see the existing examples in that header.

OK.

Thanks,
Dongxiao

> 
> Ian.

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