[libvirt] [RFC PATCH 2/2] conf: Extend cputune/cachetune to support memory bandwidth allocation

[bing.niu]

Hi Jano,
Thanks for review, please see my response.

On 2018年06月02日 22:54, Ján Tomko wrote:
> On Tue, May 29, 2018 at 06:58:03PM +0800, bing.niu at intel.com wrote:
>> From: Bing Niu <bing.niu at intel.com>
>>
>> Extend current cachetune section to support memory bandwidth allocation.
>> Add a new cachetune element llc for memory allocation. As the example
>> below:
>>
>>        <cachetune vcpus='0'>
>>                <llc id='0' bandwidth='30'/>
>>        </cachetune>
>>
>> id        --- on which last level cache memory bandwidth to be set
>> bandwidth --- the memory bandwidth percent to set.
>>
>> Signed-off-by: Bing Niu <bing.niu at intel.com>
>> ---
>> src/conf/domain_conf.c | 86 
>> ++++++++++++++++++++++++++++++++++++++++++++++----
>> src/util/virresctrl.c  |  7 ++++
>> 2 files changed, 86 insertions(+), 7 deletions(-)
>>
>> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>> index d6ac47c..aba998d 100644
>> --- a/src/conf/domain_conf.c
>> +++ b/src/conf/domain_conf.c
>> @@ -18578,6 +18578,55 @@ virDomainDefParseBootOptions(virDomainDefPtr 
>> def,
>>     return ret;
>> }
>>
>> static int
>> virDomainCachetuneDefParseCache(xmlXPathContextPtr ctxt,
>> @@ -18670,6 +18719,7 @@ virDomainCachetuneDefParse(virDomainDefPtr def,
>>     ssize_t i = 0;
>>     int n;
>>     int ret = -1;
>> +    bool mba_available = false;
>>
>>     ctxt->node = node;
>>
>> @@ -18701,12 +18751,26 @@ virDomainCachetuneDefParse(virDomainDefPtr def,
>>         goto cleanup;
>>     }
>>
>> +    if ((n = virXPathNodeSet("./llc", ctxt, &nodes)) < 0) {
>> +        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>> +                       _("Cannot extract Memory Bandwidth  nodes under "
>> +                         "cachetune. try cache allocation"));
>> +    }
>> +
>> +    for (i = 0; i < n; i++) {
>> +        if (virDomainCachetuneDefParseMemoryBandwidth(ctxt, nodes[i], 
>> alloc) < 0)
>> +            goto cleanup;
>> +    }
>> +
>> +    if (n)
>> +        mba_available = true;
>> +
>>     if ((n = virXPathNodeSet("./cache", ctxt, &nodes)) < 0) {
>>         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>>                        _("Cannot extract cache nodes under cachetune"));
>> -        goto cleanup;
>> +        if (!mba_available)
>> +            goto cleanup;
> 
> Is it okay to skip cache parsing in that case?

Yes, but we need vcpu_str part below the cache parsing part. I saw the 
vcpu_str is used to create folder in virresctrl for a rdt group.
Maybe we can add inline wrapper functions to skip cache parsing part.
How do you think?
> 
>>     }
>> -
>>     for (i = 0; i < n; i++) {
>>         if (virDomainCachetuneDefParseCache(ctxt, nodes[i], alloc) < 0)
>>             goto cleanup;
>> @@ -26394,11 +26458,19 @@ virDomainCachetuneDefFormatHelper(unsigned 
>> int level,
>>     virBufferPtr buf = opaque;
>>     unsigned long long short_size = virFormatIntPretty(size, &unit);
>>
>> -    virBufferAsprintf(buf,
>> -                      "<cache id='%u' level='%u' type='%s' "
>> -                      "size='%llu' unit='%s'/>\n",
>> -                      cache, level, virCacheTypeToString(type),
>> -                      short_size, unit);
>> +    /* If type is VIR_CACHE_TYPE_LAST, this means it's a memory
>> +     * bandwidth allocation formatting request */
> 
> _TYPE_LAST values are sentinels used to iterate over all enum values
> and should never be given any other meaning.

hmm. Let me adjust callback functions to handle this explicitly.
> 
> Jano
> 
>> +    if (type == VIR_CACHE_TYPE_LAST)
>> +        virBufferAsprintf(buf,
>> +                          "<llc id='%u' bandwidth='%llu'/>\n",
>> +                          cache, size);
>> +
>