[PATCH] libxl: support getting and setting parameters for the Credit2

[Dario Faggioli]

With Credit2 being Xen default scheduler, it's definitely the case to
allow Credit2's scheduling parameters to be get and set via libvirt.

This is easy, as Credit and Credit2 have (at least as of now) the very
same parameters ('weight' and 'cap'). So we can just let credit2 pass
the scheduler-type check and the same code will work for both.

Signed-off-by: Dario Faggioli <dfaggioli at suse.com>
---
Cc: Jim Fehlig <jfehlig at suse.com>
---
 src/libxl/libxl_driver.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
index e0a8ec5c24..78ca77d0f6 100644
--- a/src/libxl/libxl_driver.c
+++ b/src/libxl/libxl_driver.c
@@ -75,6 +75,7 @@ VIR_LOG_INIT("libxl.libxl_driver");
 
 /* Number of Xen scheduler parameters */
 #define XEN_SCHED_CREDIT_NPARAM   2
+#define XEN_SCHED_CREDIT2_NPARAM  2
 
 #define LIBXL_CHECK_DOM0_GOTO(name, label) \
     do { \
@@ -4586,6 +4587,8 @@ libxlDomainGetSchedulerType(virDomainPtr dom, int *nparams)
         break;
     case LIBXL_SCHEDULER_CREDIT2:
         name = "credit2";
+        if (nparams)
+            *nparams = XEN_SCHED_CREDIT2_NPARAM;
         break;
     case LIBXL_SCHEDULER_ARINC653:
         name = "arinc653";
@@ -4632,11 +4635,11 @@ libxlDomainGetSchedulerParametersFlags(virDomainPtr dom,
     if (virDomainObjCheckActive(vm) < 0)
         goto cleanup;
 
+    /* Only credit and credit2 are supported for now. */
     sched_id = libxl_get_scheduler(cfg->ctx);
-
-    if (sched_id != LIBXL_SCHEDULER_CREDIT) {
+    if (sched_id != LIBXL_SCHEDULER_CREDIT && sched_id != LIBXL_SCHEDULER_CREDIT2) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Only 'credit' scheduler is supported"));
+                       _("Only 'credit' and 'credit2' schedulers are supported"));
         goto cleanup;
     }
 
@@ -4657,6 +4660,9 @@ libxlDomainGetSchedulerParametersFlags(virDomainPtr dom,
             goto cleanup;
     }
 
+    /* Credit and Credit2 have the same number (two) of parameters,
+     * so this is ok for both, at least as long as that stays true. */
+    G_STATIC_ASSERT(XEN_SCHED_CREDIT_NPARAM == XEN_SCHED2_CREDIT_NPARAM);
     if (*nparams > XEN_SCHED_CREDIT_NPARAM)
         *nparams = XEN_SCHED_CREDIT_NPARAM;
     ret = 0;
@@ -4711,9 +4717,11 @@ libxlDomainSetSchedulerParametersFlags(virDomainPtr dom,
 
     sched_id = libxl_get_scheduler(cfg->ctx);
 
-    if (sched_id != LIBXL_SCHEDULER_CREDIT) {
+    /* Only credit and credit2 are supported for now. */
+    sched_id = libxl_get_scheduler(cfg->ctx);
+    if (sched_id != LIBXL_SCHEDULER_CREDIT && sched_id != LIBXL_SCHEDULER_CREDIT2) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Only 'credit' scheduler is supported"));
+                       _("Only 'credit' and 'credit2' schedulers are supported"));
         goto endjob;
     }
 
-- 
2.24.1

-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
-------------------------------------------------------------------
<<This happens because _I_ choose it to happen!>> (Raistlin Majere)

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