Re: [Qemu-devel] [libvirt] [PATCH v2 3/8] Add support for fetching statistics of completed jobs

[Philipp Hahn <hahn@univention.de>]

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Hi,

FYI as tracking down that failure did cost me some time and hopefully
this summary will help other to avoid this situation:

Am 09.09.2014 um 11:54 schrieb Jiri Denemark:
> virDomainGetJobStats gains new VIR_DOMAIN_JOB_STATS_COMPLETED flag that
> can be used to fetch statistics of a completed job rather than a
> currently running job.
> 
> Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
...
> --- a/src/qemu/qemu_monitor_json.c
> +++ b/src/qemu/qemu_monitor_json.c
> @@ -2500,7 +2500,8 @@ qemuMonitorJSONGetMigrationStatusReply(virJSONValuePtr reply,
...
> -    if (status->status == QEMU_MONITOR_MIGRATION_STATUS_ACTIVE) {
> +    if (status->status == QEMU_MONITOR_MIGRATION_STATUS_ACTIVE ||
> +        status->status == QEMU_MONITOR_MIGRATION_STATUS_COMPLETED) {
>          virJSONValuePtr ram = virJSONValueObjectGet(ret, "ram");
>          if (!ram) {
>              virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
>                            _("migration was active, but RAM 'transferred' "
>                              "data was missing"));

This change from libvirt v1.2.9-rc1~203 breaks migration with
qemu-kvm-1.1.2, as that ancient implementation does *not* export
transfer statistics for completed jobs:

> qemuMonitorJSONCommandWithFd:286 : Send command '{"execute":"query-migrate","id":"libvirt-41"}' for write with FD -1
> qemuMonitorJSONIOProcessLine:179 : Line [{"return": {"status": "active", "ram": {"total": 2164654080, "remaining": 22474752, "transferred": 175117413}}, "id": "libvirt-41"}]
...
> qemuMonitorJSONCommandWithFd:286 : Send command '{"execute":"query-migrate","id":"libvirt-42"}' for write with FD -1
> qemuMonitorJSONIOProcessLine:179 : Line [{"return": {"status": "completed"}, "id": "libvirt-42"}]

As you can see, there is not "ram" section and the migration is aborted
with the message:
> internal error: migration was active, but no RAM info was set

qemu-kvm/qmp-commands.hx even states this:
> - "ram": only present if "status" is "active", it is a json-object with the
>   following RAM information (in bytes):
but the example some lines below is wrong:
> 2. Migration is done and has succeeded
> 
> -> { "execute": "query-migrate" }
> <- { "return": {
>         "status": "completed",
>         "ram":{
That example has been updated by v1.2.0-rc0~29^2~2, but forgot to update
the specification above.


The attached hack for libvirt makes migration work again for me by
making "ram" optional in case of "completed".

Philipp

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From c4f6dfb25042f420fdd1728865686552d928d90e Mon Sep 17 00:00:00 2001
Message-Id: <c4f6dfb25042f420fdd1728865686552d928d90e.1462786017.git.hahn@univention.de>
From: Philipp Hahn <hahn@univention.de>
Date: Mon, 9 May 2016 10:52:09 +0200
Subject: [PATCH] Bug #40318 libvirt: Handle qemu-kvm-1.1.2 migration
 incompatibility
Organization: Univention GmbH, Bremen, Germany
To: libvir-list@redhat.com

The change from libvirt v1.2.9-rc1~203 breaks migration with qemu-kvm-1.1.2, as
that ancient implementation does *not* export transfer statistics for completed
jobs:

> qemuMonitorJSONCommandWithFd:286 : Send command '{"execute":"query-migrate","id":"libvirt-41"}' for write with FD -1
> qemuMonitorJSONIOProcessLine:179 : Line [{"return": {"status": "active", "ram": {"total": 2164654080, "remaining": 22474752, "transferred": 175117413}}, "id": "libvirt-41"}]
...
> qemuMonitorJSONCommandWithFd:286 : Send command '{"execute":"query-migrate","id":"libvirt-42"}' for write with FD -1
> qemuMonitorJSONIOProcessLine:179 : Line [{"return": {"status": "completed"}, "id": "libvirt-42"}]

As you can see, there is not "ram" section and the migration is aborted with
the message:
> internal error: migration was active, but no RAM info was set

qemu-kvm/qmp-commands.hx even states this:
> - "ram": only present if "status" is "active", it is a json-object with the
>   following RAM information (in bytes):
but the example some lines below is wrong:
> 2. Migration is done and has succeeded
>
> -> { "execute": "query-migrate" }
> <- { "return": {
>         "status": "completed",
>         "ram":{
That example has been updated by v1.2.0-rc0~29^2~2, but forgot to update the
specification above.
---
 src/qemu/qemu_monitor_json.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index a62c02f..d3b7b90 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -2483,8 +2483,11 @@ qemuMonitorJSONGetMigrationStatusReply(virJSONValuePtr reply,
         if (!ram) {
             virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                            _("migration was active, but no RAM info was set"));
+            if (status->status == QEMU_MONITOR_MIGRATION_STATUS_ACTIVE) {
+                // qemu-kvm-1.1.2 does NOT report 'ram':{...} on complete
             return -1;
-        }
+            }
+        } else {
 
         if (virJSONValueObjectGetNumberUlong(ram, "transferred",
                                              &status->ram_transferred) < 0) {
@@ -2514,6 +2517,7 @@ qemuMonitorJSONGetMigrationStatusReply(virJSONValuePtr reply,
         virJSONValueObjectGetNumberUlong(ram, "normal", &status->ram_normal);
         virJSONValueObjectGetNumberUlong(ram, "normal-bytes",
                                          &status->ram_normal_bytes);
+        }
 
         virJSONValuePtr disk = virJSONValueObjectGet(ret, "disk");
         if (disk) {
-- 
2.1.4