Re: [Xen-devel] [PATCH 1 of 3] Support of getting scheduler defaults

[Dario Faggioli <raistlin@xxxxxxxx>]

On Wed, 2012-05-23 at 07:34 +0200, Juergen Gross wrote:
> > #define PERIOD_MAX MILLISECS(10000) /* 10s  */
> > #define PERIOD_MIN (MICROSECS(10))  /* 10us */
> > #define SLICE_MIN (MICROSECS(5))    /*  5us */
> 
> I think this should remain in the hypervisor only.
> 
Me too.

> > Also, extratime is a flag, so I think 0 and 1 are both meaningful
> > values, maybe we can go for -1 as for cap (I'll try and let you know).
> 
> Why not -1 for all values?
> 
Would work, I guess, unless there's some collision with big weights
represented on short unsigned value (not sure it's like that, and I've
always been bad at this kind of math! :-P).

> >> I'm pretty sure that libxl__sched_set_params needs to get the correct
> >> scheduler for the particular domain, but I've no idea how to get that...
> >>
> > Again, I was thinking something like what Juergen did here could help
> > (go getting the scheduler of the cpupool the domain belongs to)... O am
> > I misunderstanding the issue?
> >
> > +    poolinfo = libxl_list_cpupool(ctx,&n_pools);
> > +    if (!poolinfo)
> > +        return ERROR_NOMEM;
> > +
> > +    ret = ERROR_INVAL;
> > +    for (p = 0; p<  n_pools; p++) {
> > +        if (poolinfo[p].poolid == poolid) {
> > +            scparams->sched = poolinfo[p].sched;
> > +            ret = 0;
> > +        }
> > +        libxl_cpupoolinfo_dispose(poolinfo + p);
> > +    }
> > +
> 
> This was exactly the purpose of the sniplet.
> 
Good to hear that. :-)

> > # xl create vm1.cfg
> > Parsing config from vm1.cfg
> > libxl: error: libxl.c:3417:libxl_sched_sedf_domain_set: setting domain 
> > sched sedf: Invalid argument
> >
> > And I'm getting the above independently on what I put in the config file
> > (valid params, no params at all, etc.). I also can't change the
> > scheduling parameters of a domain on-line anymore:
> >
> > # xl sched-sedf -d 3 -p 100 -s 50
> > libxl: error: libxl.c:3417:libxl_sched_sedf_domain_set: setting domain 
> > sched sedf: Invalid argument
> > libxl_sched_sedf_domain_set failed.
> >
> > I'll try digging a bit more into this ASAP.
> 
> It's easy: Ian repeated an error he (and I) corrected elsewhere:
> He's always setting period, regardless of the changed parameter...
> 
Not sure, I think Ian's patch fixes that:

--- a/tools/libxl/xl_cmdimpl.c  Tue May 22 14:19:07 2012 +0100
+++ b/tools/libxl/xl_cmdimpl.c  Tue May 22 15:58:47 2012 +0100
@@ -627,23 +627,20 @@ static void parse_config_data(const char
 
     libxl_domain_build_info_init_type(b_info, c_info->type);
 
-    /* the following is the actual config parsing with overriding values in 
the structures */
+    /* the following is the actual config parsing with overriding
+     * values in the structures */
     if (!xlu_cfg_get_long (config, "cpu_weight", &l, 0))
         b_info->sched_params.weight = l;
     if (!xlu_cfg_get_long (config, "cap", &l, 0))
         b_info->sched_params.cap = l;
-    if (!xlu_cfg_get_long (config, "tslice_ms", &l, 0))
-        b_info->sched_params.tslice_ms = l;
-    if (!xlu_cfg_get_long (config, "ratelimit_us", &l, 0))
-        b_info->sched_params.ratelimit_us = l;
     if (!xlu_cfg_get_long (config, "period", &l, 0))
         b_info->sched_params.period = l;
     if (!xlu_cfg_get_long (config, "slice", &l, 0))
-        b_info->sched_params.period = l;
+        b_info->sched_params.slice = l;
     if (!xlu_cfg_get_long (config, "latency", &l, 0))
-        b_info->sched_params.period = l;
+        b_info->sched_params.latency = l;
     if (!xlu_cfg_get_long (config, "extratime", &l, 0))
-        b_info->sched_params.period = l;
+        b_info->sched_params.extratime = l;
 

So it has to be something else...

Thanks and Regards,
Dario

-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://retis.sssup.it/people/faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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