xl sched-credit: support long options

The help text of xl sched-credit supported long options. Neither the man page
nor the implementation did.

Signed-off-by: juergen.gross@ts.fujitsu.com
Acked-by: Ian Jackson <ian.jackson.citrix.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>

docs/man/xl.pod.1

@@ -639,25 +639,30 @@ default B<credit> is used for scheduling.
 
 =over 4
 
-=item B<sched-credit> [ B<-d> I<domain-id> [ B<-w>[B<=>I<WEIGHT>] | B<-c>[B<=>I<CAP>] ] ]
+=item B<sched-credit> [I<OPTIONS>]
 
-Set credit scheduler parameters.  The credit scheduler is a
+Set or get credit scheduler parameters.  The credit scheduler is a
 proportional fair share CPU scheduler built from the ground up to be
 work conserving on SMP hosts.
 
 Each domain (including Domain0) is assigned a weight and a cap.
 
-B<PARAMETERS>
+B<OPTIONS>
 
 =over 4
 
-=item I<WEIGHT>
+=item B<-d DOMAIN>, B<--domain=DOMAIN>
+
+Specify domain for which scheduler parameters are to be modified or retrieved.
+Mandatory for modifying scheduler parameters.
+
+=item B<-w WEIGHT>, B<--weight=WEIGHT>
 
 A domain with a weight of 512 will get twice as much CPU as a domain
 with a weight of 256 on a contended host. Legal weights range from 1
 to 65535 and the default is 256.
 
-=item I<CAP>
+=item B<-c CAP>, B<--cap=CAP>
 
 The cap optionally fixes the maximum amount of CPU a domain will be
 able to consume, even if the host system has idle CPU cycles. The cap

tools/libxl/xl_cmdimpl.c

@@ -3804,8 +3804,19 @@ int main_sched_credit(int argc, char **argv)
     const char *dom = NULL;
     int weight = 256, cap = 0, opt_w = 0, opt_c = 0;
     int opt, rc;
+    int option_index = 0;
+    static struct option long_options[] = {
+        {"domain", 1, 0, 'd'},
+        {"weight", 1, 0, 'w'},
+        {"cap", 1, 0, 'c'},
+        {"help", 0, 0, 'h'},
+        {0, 0, 0, 0}
+    };
 
-    while ((opt = def_getopt(argc, argv, "d:w:c:", "sched-credit", 0)) != -1) {
+    while (1) {
+        opt = getopt_long(argc, argv, "d:w:c:h", long_options, &option_index);
+        if (opt == -1)
+            break;
         switch (opt) {
         case 0: case 2:
             return opt;
@@ -3820,6 +3831,9 @@ int main_sched_credit(int argc, char **argv)
             cap = strtol(optarg, NULL, 10);
             opt_c = 1;
             break;
+        case 'h':
+            help("sched-credit");
+            return 0;
         }
     }