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

[Ján Tomko]

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?

>     }
>-
>     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.

Jano

>+    if (type == VIR_CACHE_TYPE_LAST)
>+        virBufferAsprintf(buf,
>+                          "<llc id='%u' bandwidth='%llu'/>\n",
>+                          cache, size);
>+

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