[libvirt] [PATCH 3/3] qemu: Report which iothread IDs are actually returned with VIR_DOMAIN_STATS_IOTHREAD

[Peter Krempa]

The design of the stats fields returned for VIR_DOMAIN_STATS_IOTHREAD
domain statistics groups deviates from the established pattern. In this
instance it's impossible to infer which values of <id> for
iothread.<id>... fields will be reported back because they have no
connection to the iothread.count field.

Introduce iothread.ids which will report a comma-separated list of <id>s
reported in the subsequent array in the order they will be reported.

virsh domstats upstream --iothread
Domain: 'upstream'
  iothread.count=2
  iothread.ids=7,5
  iothread.7.poll-max-ns=32768
  iothread.7.poll-grow=0
  iothread.7.poll-shrink=0
  iothread.5.poll-max-ns=32768
  iothread.5.poll-grow=0
  iothread.5.poll-shrink=0

Signed-off-by: Peter Krempa <pkrempa at redhat.com>
---
 src/libvirt-domain.c   |  2 ++
 src/qemu/qemu_driver.c | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/src/libvirt-domain.c b/src/libvirt-domain.c
index 87110036ca..e6d5697445 100644
--- a/src/libvirt-domain.c
+++ b/src/libvirt-domain.c
@@ -11620,6 +11620,8 @@ virConnectGetDomainCapabilities(virConnectPtr conn,
  *                        will use it's iothread_id value as the <id>. There
  *                        may be fewer <id> entries than the iothread.count
  *                        value if the polling values are not supported.
+ *     "iothread.ids" - a comma separated list of iotdread <id>s reported in the
+ *                      subsequent list reported as a string
  *     "iothread.<id>.poll-max-ns" - maximum polling time in ns as an unsigned
  *                                   long long. A 0 (zero) means polling is
  *                                   disabled.
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index b5300241a8..4ccc9d3d4e 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -21189,6 +21189,8 @@ qemuDomainGetStatsIOThread(virQEMUDriverPtr driver,
     qemuMonitorIOThreadInfoPtr *iothreads = NULL;
     int niothreads;
     int ret = -1;
+    g_auto(virBuffer) iothridbuf = VIR_BUFFER_INITIALIZER;
+    g_autofree char *iothridstr = NULL;

     if (!HAVE_JOB(privflags) || !virDomainObjIsActive(dom))
         return 0;
@@ -21205,6 +21207,15 @@ qemuDomainGetStatsIOThread(virQEMUDriverPtr driver,
     if (virTypedParamListAddUInt(params, niothreads, "iothread.count") < 0)
         goto cleanup;

+    for (i = 0; i < niothreads; i++)
+        virBufferAsprintf(&iothridbuf, "%u,", iothreads[i]->iothread_id);
+
+    virBufferTrim(&iothridbuf, ",", -1);
+    iothridstr = virBufferContentAndReset(&iothridbuf);
+
+    if (virTypedParamListAddString(params, iothridstr, "iothread.ids") < 0)
+        goto cleanup;
+
     for (i = 0; i < niothreads; i++) {
         if (iothreads[i]->poll_valid) {
             if (virTypedParamListAddULLong(params, iothreads[i]->poll_max_ns,
-- 
2.23.0