[PATCH 3 of 5] libxl: add NIC QoS parameters

[David Scott <dave.scott@eu.citrix.com>]

# HG changeset patch
# User David Scott <dave.scott@eu.citrix.com>
# Date 1301314652 -3600
# Node ID 3aab79c907a2c78f4e81362944ee65ddf6f2cc6f
# Parent  45326ad6a0d396bfcd3c83d209ab7a19d6499896
libxl: add NIC QoS parameters

The parameters are:
  qos_kib_per_sec:    maximum rate in KiB/sec
  qos_timeslice_usec: time period over which the average rate is enforced in
                      usec

One can now execute commands like
  xl network-attach ... rate=1024,50000
which should impose an average limit of 1MiB/sec, over intervals of 50ms

The "rate" key in the network backend is interpreted by netback. It wants:
  bytes_per_interval, interval_length

Signed-off-by: David Scott <dave.scott@eu.citrix.com>

diff -r 45326ad6a0d3 -r 3aab79c907a2 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Mon Mar 28 13:17:32 2011 +0100
+++ b/tools/libxl/libxl.c	Mon Mar 28 13:17:32 2011 +0100
@@ -1194,6 +1194,8 @@
                libxl_xen_script_dir_path()) < 0 )
         return ERROR_FAIL;
     nic_info->nictype = NICTYPE_IOEMU;
+    nic_info->qos_kib_per_sec = 0;
+    nic_info->qos_timeslice_usec = 0;
     return 0;
 }
 
@@ -1205,6 +1207,7 @@
     libxl__device device;
     char *dompath, **l;
     unsigned int nb, rc;
+    uint32_t bytes_per_interval; 
 
     front = flexarray_make(16, 1);
     if (!front) {
@@ -1263,6 +1266,11 @@
     flexarray_append(back, libxl__strdup(&gc, nic->bridge));
     flexarray_append(back, "handle");
     flexarray_append(back, libxl__sprintf(&gc, "%d", nic->devid));
+    if (nic->qos_timeslice_usec > 0) {
+        bytes_per_interval = (uint32_t) (((uint64_t)nic->qos_kib_per_sec * 1024L * (uint64_t)nic->qos_timeslice_usec) / 1000000L);
+        flexarray_append(back, "rate");
+        flexarray_append(back, libxl__sprintf(&gc, "%u,%u", bytes_per_interval, nic->qos_timeslice_usec));
+    }
 
     flexarray_append(front, "backend-id");
     flexarray_append(front, libxl__sprintf(&gc, "%d", nic->backend_domid));
diff -r 45326ad6a0d3 -r 3aab79c907a2 tools/libxl/libxl.idl
--- a/tools/libxl/libxl.idl	Mon Mar 28 13:17:32 2011 +0100
+++ b/tools/libxl/libxl.idl	Mon Mar 28 13:17:32 2011 +0100
@@ -225,6 +225,8 @@
     ("ifname", string),
     ("script", string),
     ("nictype", libxl_nic_type),
+    ("qos_kib_per_sec", uint32),
+    ("qos_timeslice_usec", uint32),
     ])
 
 libxl_device_net2 = Struct("device_net2", [
diff -r 45326ad6a0d3 -r 3aab79c907a2 tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c	Mon Mar 28 13:17:32 2011 +0100
+++ b/tools/libxl/xl_cmdimpl.c	Mon Mar 28 13:17:32 2011 +0100
@@ -880,7 +880,10 @@
                         nic->backend_domid = 0;
                     }
                 } else if (!strcmp(p, "rate")) {
-                    fprintf(stderr, "the rate parameter for vifs is currently not supported\n");
+                    if (sscanf(p2 + 1, "%u,%u", &(nic->qos_kib_per_sec), &(nic->qos_timeslice_usec)) != 2) {
+                        fprintf(stderr, "Specified rate parameter needs to take the form: kib_per_sec,timeslice_usec\n");
+                        break;
+                    }
                 } else if (!strcmp(p, "accel")) {
                     fprintf(stderr, "the accel parameter for vifs is currently not supported\n");
                 }
@@ -4298,6 +4301,10 @@
             free(nic.model);
             nic.model = strdup((*argv) + 6);
         } else if (!strncmp("rate=", *argv, 5)) {
+            if (sscanf((*argv) + 5, "%u,%u", &(nic.qos_kib_per_sec), &(nic.qos_timeslice_usec)) != 2) {
+                fprintf(stderr, "Specified rate parameter needs to take the form: kib_per_sec,timeslice_usec\n");
+                return 1;
+            }
         } else if (!strncmp("accel=", *argv, 6)) {
         } else {
             fprintf(stderr, "unrecognized argument `%s'\n", *argv);