[RESEND PATCH 0/2] migration: Report migration related thread pid to libvirt to support migration pin

[RESEND PATCH 0/2] migration: Report migration related thread pid to libvirt to support migration pin

[Jiang Jiacheng via]

By default, the migration thread shares CPU resources with the VM process. 
With migration pin, support pin migration thread to expected CPU list 
to avoid preempting CPU resources of VM process.
To support migration pin, we need report migration related thread pid 
to libvirt.

libvirt patches:
https://listman.redhat.com/archives/libvir-list/2023-January/236561.html

Zheng Chuan (2):
  migration: report migration related thread pid to libvirt
  migration: report multiFd related thread pid to libvirt

 migration/migration.c |  3 +++
 migration/multifd.c   |  4 ++++
 qapi/migration.json   | 24 ++++++++++++++++++++++++
 3 files changed, 31 insertions(+)

-- 
2.33.0

[RESEND PATCH 1/2] migration: report migration related thread pid to libvirt

[Jiang Jiacheng via]

From: Zheng Chuan <zhengchuan@huawei.com>

Report migration thread pid to libvirt in order to pin
migration thread to different cpu.
---
 migration/migration.c |  3 +++
 qapi/migration.json   | 12 ++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/migration/migration.c b/migration/migration.c
index 52b5d39244..2534e5a1f1 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3955,6 +3955,9 @@ static void *migration_thread(void *opaque)
     MigThrError thr_error;
     bool urgent = false;
 
+    /* report migration thread pid to libvirt */
+    qapi_event_send_migration_pid(qemu_get_thread_id());
+
     rcu_register_thread();
 
     object_ref(OBJECT(s));
diff --git a/qapi/migration.json b/qapi/migration.json
index 88ecf86ac8..aafc940617 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1286,6 +1286,18 @@
 { 'event': 'MIGRATION_PASS',
   'data': { 'pass': 'int' } }
 
+##
+# @MIGRATION_PID:
+#
+# Emitted when migration thread appear
+#
+# @pid: pid of migration thread
+#
+# Since: 7.2
+##
+{ 'event': 'MIGRATION_PID',
+  'data': { 'pid': 'int' } }
+
 ##
 # @COLOMessage:
 #
-- 
2.33.0

[RESEND PATCH 2/2] migration: report multiFd related thread pid to libvirt

[Jiang Jiacheng via]

From: Zheng Chuan <zhengchuan@huawei.com>

Report multiFd related thread pid to libvirt in order to
pin multiFd thread to different cpu.
---
 migration/multifd.c |  4 ++++
 qapi/migration.json | 12 ++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/migration/multifd.c b/migration/multifd.c
index 000ca4d4ec..f3f7e8ae31 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -17,6 +17,7 @@
 #include "exec/ramblock.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
+#include "qapi/qapi-events-migration.h"
 #include "ram.h"
 #include "migration.h"
 #include "socket.h"
@@ -650,6 +651,9 @@ static void *multifd_send_thread(void *opaque)
     int ret = 0;
     bool use_zero_copy_send = migrate_use_zero_copy_send();
 
+    /* report multifd thread pid to libvirt */
+    qapi_event_send_migration_multifd_pid(qemu_get_thread_id());
+
     trace_multifd_send_thread_start(p->id);
     rcu_register_thread();
 
diff --git a/qapi/migration.json b/qapi/migration.json
index aafc940617..33fc319329 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1286,6 +1286,18 @@
 { 'event': 'MIGRATION_PASS',
   'data': { 'pass': 'int' } }
 
+##
+# @MIGRATION_MULTIFD_PID:
+#
+# Emitted when multifd thread appear
+#
+# @pid: pid of multifd thread
+#
+# Since: 7.2
+##
+{ 'event': 'MIGRATION_MULTIFD_PID',
+  'data': { 'pid': 'int' } }
+
 ##
 # @MIGRATION_PID:
 #
-- 
2.33.0

Re: [RESEND PATCH 2/2] migration: report multiFd related thread pid to libvirt

[Dr. David Alan Gilbert]

* Jiang Jiacheng via (qemu-devel@nongnu.org) wrote:
> From: Zheng Chuan <zhengchuan@huawei.com>
> 
> Report multiFd related thread pid to libvirt in order to
> pin multiFd thread to different cpu.

With multifd you may well want to pin different multifd threads
to different cores; so you need to include the 'id' and 'name' fields of
the multifd thread in the event.

(Copying in Jiri and Dan )

Dave

> ---
>  migration/multifd.c |  4 ++++
>  qapi/migration.json | 12 ++++++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 000ca4d4ec..f3f7e8ae31 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -17,6 +17,7 @@
>  #include "exec/ramblock.h"
>  #include "qemu/error-report.h"
>  #include "qapi/error.h"
> +#include "qapi/qapi-events-migration.h"
>  #include "ram.h"
>  #include "migration.h"
>  #include "socket.h"
> @@ -650,6 +651,9 @@ static void *multifd_send_thread(void *opaque)
>      int ret = 0;
>      bool use_zero_copy_send = migrate_use_zero_copy_send();
>  
> +    /* report multifd thread pid to libvirt */
> +    qapi_event_send_migration_multifd_pid(qemu_get_thread_id());
> +
>      trace_multifd_send_thread_start(p->id);
>      rcu_register_thread();
>  
> diff --git a/qapi/migration.json b/qapi/migration.json
> index aafc940617..33fc319329 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -1286,6 +1286,18 @@
>  { 'event': 'MIGRATION_PASS',
>    'data': { 'pass': 'int' } }
>  
> +##
> +# @MIGRATION_MULTIFD_PID:
> +#
> +# Emitted when multifd thread appear
> +#
> +# @pid: pid of multifd thread
> +#
> +# Since: 7.2
> +##
> +{ 'event': 'MIGRATION_MULTIFD_PID',
> +  'data': { 'pid': 'int' } }
> +
>  ##
>  # @MIGRATION_PID:
>  #
> -- 
> 2.33.0
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [RESEND PATCH 2/2] migration: report multiFd related thread pid to libvirt

[Daniel P. Berrangé]

On Wed, Jan 11, 2023 at 07:00:53PM +0000, Dr. David Alan Gilbert wrote:
> * Jiang Jiacheng via (qemu-devel@nongnu.org) wrote:
> > From: Zheng Chuan <zhengchuan@huawei.com>
> > 
> > Report multiFd related thread pid to libvirt in order to
> > pin multiFd thread to different cpu.
> 
> With multifd you may well want to pin different multifd threads
> to different cores; so you need to include the 'id' and 'name' fields of
> the multifd thread in the event.

Are the 'id' / 'name' fields considered stable API for QEMU ?

IIRC, the mgmt app merely requests the number of multifd threads
and doesn't assign any identifying names/ids to them, unlike
iothreads where the mgmt app gives an explicit 'id'.


With regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|

Re: [RESEND PATCH 2/2] migration: report multiFd related thread pid to libvirt

[Jiang Jiacheng via]

On 2023/1/12 3:04, Daniel P. Berrangé wrote:
> On Wed, Jan 11, 2023 at 07:00:53PM +0000, Dr. David Alan Gilbert wrote:
>> * Jiang Jiacheng via (qemu-devel@nongnu.org) wrote:
>>> From: Zheng Chuan <zhengchuan@huawei.com>
>>>
>>> Report multiFd related thread pid to libvirt in order to
>>> pin multiFd thread to different cpu.
>>
>> With multifd you may well want to pin different multifd threads
>> to different cores; so you need to include the 'id' and 'name' fields of
>> the multifd thread in the event.
> 
> Are the 'id' / 'name' fields considered stable API for QEMU ?
> 
> IIRC, the mgmt app merely requests the number of multifd threads
> and doesn't assign any identifying names/ids to them, unlike
> iothreads where the mgmt app gives an explicit 'id'.
> 
> 

If the 'id'/'name' of the migration thread is fixed in QEMU API, I think
the related information can be added to the mgmt app to implement
migration thread pin more properly.
And we are considering another choice, which provides a list of
migration thread information for the mgmt app to actively query, so as
to provide more information and avoid exposing thread PIDs to the mgmt
app's public API.

Thanks
Jiang Jiacheng