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

[Juergen Gross <juergen.gross@ts.fujitsu.com>]

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
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