Re: [Xen-devel] [PATCH v1 2/4] libxc: add rt scheduler

[Meng Xu <xumengpanda@xxxxxxxxx>]

2014-09-05 6:34 GMT-04:00 Dario Faggioli <dario.faggioli@xxxxxxxxxx>:
> On dom, 2014-08-24 at 18:58 -0400, Meng Xu wrote:
>
>> --- /dev/null
>> +++ b/tools/libxc/xc_rt.c
>> @@ -0,0 +1,90 @@
>> +/****************************************************************************
>> + *
>> + *        File: xc_rt.c
>> + *      Author: Sisu Xi
>> + *              Meng Xu
>> + *
>> + * Description: XC Interface to the rt scheduler
>> + *
>> + * This library is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Lesser General Public
>> + * License as published by the Free Software Foundation;
>> + * version 2.1 of the License.
>> + *
>> + * This library is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * Lesser General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU Lesser General Public
>> + * License along with this library; if not, write to the Free Software
>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  
>> 02110-1301  USA
>> + */
>> +
>> +#include "xc_private.h"
>> +
>> +int xc_sched_rt_domain_set(xc_interface *xch,
>> +                           uint32_t domid,
>> +                           struct xen_domctl_sched_rt_params *sdom)
>> +{
>> +    int rc;
>> +    DECLARE_DOMCTL;
>> +
>> +    domctl.cmd = XEN_DOMCTL_scheduler_op;
>> +    domctl.domain = (domid_t) domid;
>> +    domctl.u.scheduler_op.sched_id = XEN_SCHEDULER_RT_DS;
>>
> Aha! So, I was not dreaming about the whole RT_DS thing! :-D
>
> Perhaps then had that discussion about the low level side of things
> then. Well, I think that, if the name of the scheduler is RT_DS, it
> should be that for libxl and xl as well.
>
> After all, the reason why we're calling RT_DS in Xen, is that we want to
> be able to add others RT_FOO, RT_BAR algorithm/schedulers, in future. If
> that will happen, we'll need a way to reference them from the higher
> layer of the toolstack as well. When we'll have RT_DS and RT_CBS in Xen,
> and RT in libxl, to which one the RT in libxl will refer?
>
> So, just push the RT_DS thing all the way up to libxl and xl. As we said
> for the Xen part, you can keep the source filenames _rt.c, but functions
> and defines needs to be specific.
>
> So, for instance, this file can continue being xc_rt.c, but this
> function needs to be called xc_sched_rtds_domain_set()
> (or .._rt_ds_domain_..)

As to the function name, if I change it to ..._rt_ds_domain_... in
xc_rt.c file, do I need to change it in libxl and xl files? In
addition, do I need to change the name rt_* functions in
xen/common/sched_rt.c in the hypervisor? This seems a lot of (well
easy) change, but we need some consensus to avoid changing it back
later. :-P

>
>> +    domctl.u.scheduler_op.cmd = XEN_DOMCTL_SCHEDOP_putinfo;
>> +    domctl.u.scheduler_op.u.rt.vcpu_index = sdom->index;
>> +    domctl.u.scheduler_op.u.rt.period = sdom->period;
>> +    domctl.u.scheduler_op.u.rt.budget = sdom->budget;
>> +
>> +    rc = do_domctl(xch, &domctl);
>> +
>> +    return rc;
>> +}
>> +
> These functions are going to change quite a bit in next version, due to
> the interface changes we agreed upon. It'd then be quite pointless to
> put much more comments, but, overall, the hcall wrapping, the bouncing
> logic, and everything I can see here looks fine to me.
>

I will send the next version soon.

-----------
Meng Xu
PhD Student in Computer and Information Science
University of Pennsylvania

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