1. Patchew
  2. QEMU
  3. [Qemu-devel] [PATCH V5 0/9] calculate blocktime for postcopy live migration
  4. View patch

[Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability

Alexey Perevalov posted 9 patches 8 years, 9 months ago
There is a newer version of this series
[Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability
Posted by Alexey Perevalov 8 years, 9 months ago 
Right now it could be used on destination side to
enable vCPU blocktime calculation for postcopy live migration.
vCPU blocktime - it's time since vCPU thread was put into
interruptible sleep, till memory page was copied and thread awake.

Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
---
 include/migration/migration.h | 1 +
 migration/migration.c         | 9 +++++++++
 qapi-schema.json              | 5 ++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index ba1a16c..82bbcd8 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -315,6 +315,7 @@ int migrate_compress_level(void);
 int migrate_compress_threads(void);
 int migrate_decompress_threads(void);
 bool migrate_use_events(void);
+bool migrate_postcopy_blocktime(void);
 
 /* Sending on the return path - generic and then for each message type */
 void migrate_send_rp_message(MigrationIncomingState *mis,
diff --git a/migration/migration.c b/migration/migration.c
index 569a7f6..c0443ce 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1371,6 +1371,15 @@ bool migrate_zero_blocks(void)
     return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
 }
 
+bool migrate_postcopy_blocktime(void)
+{
+    MigrationState *s;
+
+    s = migrate_get_current();
+
+    return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME];
+}
+
 bool migrate_use_compression(void)
 {
     MigrationState *s;
diff --git a/qapi-schema.json b/qapi-schema.json
index 01b087f..fde6d63 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -894,11 +894,14 @@
 # @release-ram: if enabled, qemu will free the migrated ram pages on the source
 #        during postcopy-ram migration. (since 2.9)
 #
+# @postcopy-blocktime: Calculate downtime for postcopy live migration (since 2.10)
+#
 # Since: 1.2
 ##
 { 'enum': 'MigrationCapability',
   'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
-           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] }
+           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
+           'postcopy-blocktime'] }
 
 ##
 # @MigrationCapabilityStatus:
-- 
1.9.1
Re: [Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability
Posted by Dr. David Alan Gilbert 8 years, 9 months ago 
* Alexey Perevalov (a.perevalov@samsung.com) wrote:
> Right now it could be used on destination side to
> enable vCPU blocktime calculation for postcopy live migration.
> vCPU blocktime - it's time since vCPU thread was put into
> interruptible sleep, till memory page was copied and thread awake.
> 
> Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  include/migration/migration.h | 1 +
>  migration/migration.c         | 9 +++++++++
>  qapi-schema.json              | 5 ++++-
>  3 files changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index ba1a16c..82bbcd8 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -315,6 +315,7 @@ int migrate_compress_level(void);
>  int migrate_compress_threads(void);
>  int migrate_decompress_threads(void);
>  bool migrate_use_events(void);
> +bool migrate_postcopy_blocktime(void);
>  
>  /* Sending on the return path - generic and then for each message type */
>  void migrate_send_rp_message(MigrationIncomingState *mis,
> diff --git a/migration/migration.c b/migration/migration.c
> index 569a7f6..c0443ce 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1371,6 +1371,15 @@ bool migrate_zero_blocks(void)
>      return s->enabled_capabilities[MIGRATION_CAPABILITY_ZERO_BLOCKS];
>  }
>  
> +bool migrate_postcopy_blocktime(void)
> +{
> +    MigrationState *s;
> +
> +    s = migrate_get_current();
> +
> +    return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_BLOCKTIME];
> +}
> +
>  bool migrate_use_compression(void)
>  {
>      MigrationState *s;
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 01b087f..fde6d63 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -894,11 +894,14 @@
>  # @release-ram: if enabled, qemu will free the migrated ram pages on the source
>  #        during postcopy-ram migration. (since 2.9)
>  #
> +# @postcopy-blocktime: Calculate downtime for postcopy live migration (since 2.10)
> +#
>  # Since: 1.2
>  ##
>  { 'enum': 'MigrationCapability',
>    'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
> -           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] }
> +           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
> +           'postcopy-blocktime'] }
>  
>  ##
>  # @MigrationCapabilityStatus:
> -- 
> 1.9.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Re: [Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability
Posted by Eric Blake 8 years, 8 months ago 
On 05/12/2017 08:31 AM, Alexey Perevalov wrote:
> Right now it could be used on destination side to
> enable vCPU blocktime calculation for postcopy live migration.
> vCPU blocktime - it's time since vCPU thread was put into
> interruptible sleep, till memory page was copied and thread awake.
> 
> Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
> ---
>  include/migration/migration.h | 1 +
>  migration/migration.c         | 9 +++++++++
>  qapi-schema.json              | 5 ++++-
>  3 files changed, 14 insertions(+), 1 deletion(-)
> 

> +++ b/qapi-schema.json
> @@ -894,11 +894,14 @@
>  # @release-ram: if enabled, qemu will free the migrated ram pages on the source
>  #        during postcopy-ram migration. (since 2.9)
>  #
> +# @postcopy-blocktime: Calculate downtime for postcopy live migration (since 2.10)
> +#
>  # Since: 1.2
>  ##
>  { 'enum': 'MigrationCapability',
>    'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
> -           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] }
> +           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
> +           'postcopy-blocktime'] }

Why does this need to be a capability that we have to turn on, and not
something that is collected unconditionally? Is there a drawback to
having the stat collection always enabled without a capability?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org
Re: [Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability
Posted by Alexey 8 years, 8 months ago 
On Mon, May 22, 2017 at 11:20:13AM -0500, Eric Blake wrote:
> On 05/12/2017 08:31 AM, Alexey Perevalov wrote:
> > Right now it could be used on destination side to
> > enable vCPU blocktime calculation for postcopy live migration.
> > vCPU blocktime - it's time since vCPU thread was put into
> > interruptible sleep, till memory page was copied and thread awake.
> > 
> > Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
> > ---
> >  include/migration/migration.h | 1 +
> >  migration/migration.c         | 9 +++++++++
> >  qapi-schema.json              | 5 ++++-
> >  3 files changed, 14 insertions(+), 1 deletion(-)
> > 
> 
> > +++ b/qapi-schema.json
> > @@ -894,11 +894,14 @@
> >  # @release-ram: if enabled, qemu will free the migrated ram pages on the source
> >  #        during postcopy-ram migration. (since 2.9)
> >  #
> > +# @postcopy-blocktime: Calculate downtime for postcopy live migration (since 2.10)
> > +#
> >  # Since: 1.2
> >  ##
> >  { 'enum': 'MigrationCapability',
> >    'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
> > -           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] }
> > +           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
> > +           'postcopy-blocktime'] }
> 
> Why does this need to be a capability that we have to turn on, and not
> something that is collected unconditionally? Is there a drawback to
> having the stat collection always enabled without a capability?
yes, it has a performance penalty
(runtime complexity O(n) + O(m), where n is vCPU number, m is number of memory
pages), but not so huge, compared to network
latencies, also memory usage, but no more than 0.03% of QEMU's total
memory.

> 
> -- 
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266
> Virtualization:  qemu.org | libvirt.org
> 



-- 

BR
Alexey
Re: [Qemu-devel] [PATCH V5 5/9] migration: introduce postcopy-blocktime capability
Posted by Dr. David Alan Gilbert 8 years, 8 months ago 
* Eric Blake (eblake@redhat.com) wrote:
> On 05/12/2017 08:31 AM, Alexey Perevalov wrote:
> > Right now it could be used on destination side to
> > enable vCPU blocktime calculation for postcopy live migration.
> > vCPU blocktime - it's time since vCPU thread was put into
> > interruptible sleep, till memory page was copied and thread awake.
> > 
> > Signed-off-by: Alexey Perevalov <a.perevalov@samsung.com>
> > ---
> >  include/migration/migration.h | 1 +
> >  migration/migration.c         | 9 +++++++++
> >  qapi-schema.json              | 5 ++++-
> >  3 files changed, 14 insertions(+), 1 deletion(-)
> > 
> 
> > +++ b/qapi-schema.json
> > @@ -894,11 +894,14 @@
> >  # @release-ram: if enabled, qemu will free the migrated ram pages on the source
> >  #        during postcopy-ram migration. (since 2.9)
> >  #
> > +# @postcopy-blocktime: Calculate downtime for postcopy live migration (since 2.10)
> > +#
> >  # Since: 1.2
> >  ##
> >  { 'enum': 'MigrationCapability',
> >    'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
> > -           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] }
> > +           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
> > +           'postcopy-blocktime'] }
> 
> Why does this need to be a capability that we have to turn on, and not
> something that is collected unconditionally? Is there a drawback to
> having the stat collection always enabled without a capability?

Yes, there was a reasonable CPU/memory overhead.
(Although it might be lower now).

Dave

> -- 
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266
> Virtualization:  qemu.org | libvirt.org
> 



--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Patchew 2.1-devel-b67e4c2

© 2016 - 2026 Red Hat, Inc.