Re: [Xen-devel] [PATCH 4 of 4] Support new xl command cpupool-numa-split

[Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>]

On 12/08/10 12:16, Ian Campbell wrote:
> On Fri, 2010-11-26 at 07:10 +0000, Juergen Gross wrote:
> > +
> > +    if (libxl_cpumap_alloc(&ctx,&cpumap)) {
> > +        fprintf(stderr, "Failed to allocate cpumap\n");
> > +        return -ERROR_FAIL;
> > +    }
> > +
> > +    poolinfo = libxl_list_cpupool(&ctx,&n_pools);
> > +    if (!poolinfo) {
> > +        fprintf(stderr, "error getting cpupool info\n");
> > +        return -ERROR_NOMEM;
> > +    }
> > +    poolid = poolinfo[0].poolid;
> > +    schedid = poolinfo[0].sched_id;
> > +    libxl_for_each_cpu(c, poolinfo[0].cpumap)
> > +        if (libxl_cpumap_test(&poolinfo[0].cpumap, c))
> > +            libxl_cpumap_set(&cpumap, c);
> Can the libxl_cpumap_alloc and this loop be deferred until after the
> check and bail for n_pools>  1?
Sure.

> There seems to be no way to find out the number of pools without also
> getting all the info about them, which is a shame.
Taking a quick look I couldn't spot any way how to find out the number
of domains without also getting all the info about them, too...

> > +    /* Reset Pool-0 to 1st node */
> > +    node = topology->nodemap.array[0];
> > +    libxl_for_each_cpu(c, cpumap) {
> > +        if (!libxl_cpumap_test(&cpumap, c)&&  (c<  topology->nodemap.entries)&&
> > +            (topology->nodemap.array[c] == node)) {
> > +            ret = -libxl_cpupool_cpuadd(&ctx, poolid, c);
> > +            if (ret) {
> > +                fprintf(stderr, "error on adding cpu to Pool-0\n");
> > +                goto out;
> > +            }
> > +            libxl_cpumap_reset(&freemap, c);
> (nt really related to this series but I wish this was called
> libxl_cpumap_clear, I had to go check it wasn't resetting the whole map
> or something...)
Hmm, do you really think so?
It would make me to check whether it is clearing the whole map :-)
I think the second parameter is a strong hint :-)

> > +        }
> > +    }
> > +    libxl_for_each_cpu(c, cpumap) {
> > +        if (libxl_cpumap_test(&cpumap, c)&&  (c<  topology->nodemap.entries)&&
> > +            (topology->nodemap.array[c] != node)) {
> > +            ret = -libxl_cpupool_cpuremove(&ctx, poolid, c);
> > +            if (ret) {
> > +                fprintf(stderr, "error on removing cpu from Pool-0\n");
> > +                goto out;
> > +            }
> > +            libxl_cpumap_set(&freemap, c);
> > +        }
> > +    }
> Can this loop be merged with the preceding loop, with the body being the
> else case of the if?
No. I have to add new cpus first to avoid a cpupool without cpus in between.

> > +    for (;;) {
> > +        node = -1;
> > +        libxl_for_each_cpu(c, freemap) {
> > +            if (libxl_cpumap_test(&freemap, c)&&  (node == -1)) {
> > +                node = topology->nodemap.array[c];
> > +            }
> > +            libxl_cpumap_reset(&cpumap, c);
> > +            if ((node>= 0)&&  libxl_cpumap_test(&freemap, c)&&
> > +                (c<  topology->nodemap.entries)&&  (topology->nodemap.array[c] 
> > == node)) {
> > +                libxl_cpumap_reset(&freemap, c);
> > +                libxl_cpumap_set(&cpumap, c);
> > +            }
> > +        }
> > +        if (node == -1)
> > +            break;
> > +
> > +        snprintf(name, 15, "Pool-node%d", node);
> Do we want to rename Pool-0 at some point too or do we rely on that name
> elsewhere?
Good question. There is a hard coded "Pool-0" reference in libxl, but this
could easily be changed.
I'm not sure about implications in xm/xend. I'll check this.


Juergen

--
Juergen Gross                 Principal Developer Operating Systems
TSP ES&S SWE OS6                       Telephone: +49 (0) 89 3222 2967
Fujitsu Technology Solutions              e-mail: juergen.gross@xxxxxxxxxxxxxx
Domagkstr. 28                           Internet: ts.fujitsu.com
D-80807 Muenchen                 Company details: ts.fujitsu.com/imprint.html

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