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[Qemu-devel] [PATCH 2/5] migration: add the interface to set get_return_path

Lidong Chen posted 5 patches 7 years, 10 months ago
There is a newer version of this series
[Qemu-devel] [PATCH 2/5] migration: add the interface to set get_return_path
Posted by Lidong Chen 7 years, 10 months ago 
The default get_return_path function of iochannel does not work for
RDMA live migration. So add the interface to set get_return_path.

Signed-off-by: Lidong Chen <lidongchen@tencent.com>
---
 migration/qemu-file-channel.c | 12 ++++++++----
 migration/qemu-file.c         | 10 ++++++++--
 migration/qemu-file.h         |  2 +-
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
index e202d73..d4dd8c4 100644
--- a/migration/qemu-file-channel.c
+++ b/migration/qemu-file-channel.c
@@ -156,7 +156,6 @@ static const QEMUFileOps channel_input_ops = {
     .close = channel_close,
     .shut_down = channel_shutdown,
     .set_blocking = channel_set_blocking,
-    .get_return_path = channel_get_input_return_path,
 };
 
 
@@ -165,18 +164,23 @@ static const QEMUFileOps channel_output_ops = {
     .close = channel_close,
     .shut_down = channel_shutdown,
     .set_blocking = channel_set_blocking,
-    .get_return_path = channel_get_output_return_path,
 };
 
 
 QEMUFile *qemu_fopen_channel_input(QIOChannel *ioc)
 {
+    QEMUFile *f;
     object_ref(OBJECT(ioc));
-    return qemu_fopen_ops(ioc, &channel_input_ops);
+    f = qemu_fopen_ops(ioc, &channel_input_ops);
+    qemu_file_set_return_path(f, channel_get_input_return_path);
+    return f;
 }
 
 QEMUFile *qemu_fopen_channel_output(QIOChannel *ioc)
 {
+    QEMUFile *f;
     object_ref(OBJECT(ioc));
-    return qemu_fopen_ops(ioc, &channel_output_ops);
+    f = qemu_fopen_ops(ioc, &channel_output_ops);
+    qemu_file_set_return_path(f, channel_get_output_return_path);
+    return f;
 }
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index bb63c77..8acb574 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -36,6 +36,7 @@
 struct QEMUFile {
     const QEMUFileOps *ops;
     const QEMUFileHooks *hooks;
+    QEMURetPathFunc *get_return_path;
     void *opaque;
 
     int64_t bytes_xfer;
@@ -72,10 +73,15 @@ int qemu_file_shutdown(QEMUFile *f)
  */
 QEMUFile *qemu_file_get_return_path(QEMUFile *f)
 {
-    if (!f->ops->get_return_path) {
+    if (!f->get_return_path) {
         return NULL;
     }
-    return f->ops->get_return_path(f->opaque);
+    return f->get_return_path(f->opaque);
+}
+
+void qemu_file_set_return_path(QEMUFile *f, QEMURetPathFunc *get_return_path)
+{
+    f->get_return_path = get_return_path;
 }
 
 bool qemu_file_mode_is_not_valid(const char *mode)
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index f4f356a..74210b7 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -102,7 +102,6 @@ typedef struct QEMUFileOps {
     QEMUFileCloseFunc *close;
     QEMUFileSetBlocking *set_blocking;
     QEMUFileWritevBufferFunc *writev_buffer;
-    QEMURetPathFunc *get_return_path;
     QEMUFileShutdownFunc *shut_down;
 } QEMUFileOps;
 
@@ -114,6 +113,7 @@ typedef struct QEMUFileHooks {
 } QEMUFileHooks;
 
 QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
+void qemu_file_set_return_path(QEMUFile *f, QEMURetPathFunc *get_return_path);
 void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks);
 int qemu_get_fd(QEMUFile *f);
 int qemu_fclose(QEMUFile *f);
-- 
1.8.3.1
Re: [Qemu-devel] [PATCH 2/5] migration: add the interface to set get_return_path
Posted by Dr. David Alan Gilbert 7 years, 10 months ago 
* Lidong Chen (jemmy858585@gmail.com) wrote:
> The default get_return_path function of iochannel does not work for
> RDMA live migration. So add the interface to set get_return_path.
> 
> Signed-off-by: Lidong Chen <lidongchen@tencent.com>

Lets see how Dan wants this done, he knows the channel/file stuff;
to me this feels like it should be adding a member to QIOChannelClass
that gets used by QEMUFile's get_return_path.

(Dan and see next patch)

Dave
> ---
>  migration/qemu-file-channel.c | 12 ++++++++----
>  migration/qemu-file.c         | 10 ++++++++--
>  migration/qemu-file.h         |  2 +-
>  3 files changed, 17 insertions(+), 7 deletions(-)
> 
> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> index e202d73..d4dd8c4 100644
> --- a/migration/qemu-file-channel.c
> +++ b/migration/qemu-file-channel.c
> @@ -156,7 +156,6 @@ static const QEMUFileOps channel_input_ops = {
>      .close = channel_close,
>      .shut_down = channel_shutdown,
>      .set_blocking = channel_set_blocking,
> -    .get_return_path = channel_get_input_return_path,
>  };
>  
>  
> @@ -165,18 +164,23 @@ static const QEMUFileOps channel_output_ops = {
>      .close = channel_close,
>      .shut_down = channel_shutdown,
>      .set_blocking = channel_set_blocking,
> -    .get_return_path = channel_get_output_return_path,
>  };
>  
>  
>  QEMUFile *qemu_fopen_channel_input(QIOChannel *ioc)
>  {
> +    QEMUFile *f;
>      object_ref(OBJECT(ioc));
> -    return qemu_fopen_ops(ioc, &channel_input_ops);
> +    f = qemu_fopen_ops(ioc, &channel_input_ops);
> +    qemu_file_set_return_path(f, channel_get_input_return_path);
> +    return f;
>  }
>  
>  QEMUFile *qemu_fopen_channel_output(QIOChannel *ioc)
>  {
> +    QEMUFile *f;
>      object_ref(OBJECT(ioc));
> -    return qemu_fopen_ops(ioc, &channel_output_ops);
> +    f = qemu_fopen_ops(ioc, &channel_output_ops);
> +    qemu_file_set_return_path(f, channel_get_output_return_path);
> +    return f;
>  }
> diff --git a/migration/qemu-file.c b/migration/qemu-file.c
> index bb63c77..8acb574 100644
> --- a/migration/qemu-file.c
> +++ b/migration/qemu-file.c
> @@ -36,6 +36,7 @@
>  struct QEMUFile {
>      const QEMUFileOps *ops;
>      const QEMUFileHooks *hooks;
> +    QEMURetPathFunc *get_return_path;
>      void *opaque;
>  
>      int64_t bytes_xfer;
> @@ -72,10 +73,15 @@ int qemu_file_shutdown(QEMUFile *f)
>   */
>  QEMUFile *qemu_file_get_return_path(QEMUFile *f)
>  {
> -    if (!f->ops->get_return_path) {
> +    if (!f->get_return_path) {
>          return NULL;
>      }
> -    return f->ops->get_return_path(f->opaque);
> +    return f->get_return_path(f->opaque);
> +}
> +
> +void qemu_file_set_return_path(QEMUFile *f, QEMURetPathFunc *get_return_path)
> +{
> +    f->get_return_path = get_return_path;
>  }
>  
>  bool qemu_file_mode_is_not_valid(const char *mode)
> diff --git a/migration/qemu-file.h b/migration/qemu-file.h
> index f4f356a..74210b7 100644
> --- a/migration/qemu-file.h
> +++ b/migration/qemu-file.h
> @@ -102,7 +102,6 @@ typedef struct QEMUFileOps {
>      QEMUFileCloseFunc *close;
>      QEMUFileSetBlocking *set_blocking;
>      QEMUFileWritevBufferFunc *writev_buffer;
> -    QEMURetPathFunc *get_return_path;
>      QEMUFileShutdownFunc *shut_down;
>  } QEMUFileOps;
>  
> @@ -114,6 +113,7 @@ typedef struct QEMUFileHooks {
>  } QEMUFileHooks;
>  
>  QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops);
> +void qemu_file_set_return_path(QEMUFile *f, QEMURetPathFunc *get_return_path);
>  void qemu_file_set_hooks(QEMUFile *f, const QEMUFileHooks *hooks);
>  int qemu_get_fd(QEMUFile *f);
>  int qemu_fclose(QEMUFile *f);
> -- 
> 1.8.3.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Re: [Qemu-devel] [PATCH 2/5] migration: add the interface to set get_return_path
Posted by Daniel P. Berrangé 7 years, 10 months ago 
On Wed, Apr 11, 2018 at 06:18:18PM +0100, Dr. David Alan Gilbert wrote:
> * Lidong Chen (jemmy858585@gmail.com) wrote:
> > The default get_return_path function of iochannel does not work for
> > RDMA live migration. So add the interface to set get_return_path.
> > 
> > Signed-off-by: Lidong Chen <lidongchen@tencent.com>
> 
> Lets see how Dan wants this done, he knows the channel/file stuff;
> to me this feels like it should be adding a member to QIOChannelClass
> that gets used by QEMUFile's get_return_path.

No that doesn't really fit the model. IMHO the entire concept of a separate
return path object is really wrong. The QIOChannel implementations are
(almost) all capable of bi-directional I/O, which is why the the get_retun_path
function just creates a second QEMUFile pointing to the same QIOChannel
object we already had. Migration only needs the second QEMUFile, because that
struct re-uses the same struct fields for tracking different bits of info
depending on which direction you're doing I/O in. A real fix would be to
stop overloading the same fields for multiple purposes in the QEMUFile, so
that we only needed a single QEMUFile instance.

Ignoring that though, the particular problem we're facing here is that the
QIOChannelRDMA impl that is used is not written in a way that allows
bi-directional I/O, despite the RDMA code it uses being capable of it.

So rather than changing this get_return_path code, IMHO, the right fix to
simply improve the QIOChannelRDMA impl so that it fully supports bi-directional
I/O like all the other channels do.

Regards,
Daniel
-- 
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Re: [Qemu-devel] [PATCH 2/5] migration: add the interface to set get_return_path
Posted by 858585 jemmy 7 years, 10 months ago 
On Thu, Apr 12, 2018 at 4:28 PM, Daniel P. Berrangé <berrange@redhat.com> wrote:
> On Wed, Apr 11, 2018 at 06:18:18PM +0100, Dr. David Alan Gilbert wrote:
>> * Lidong Chen (jemmy858585@gmail.com) wrote:
>> > The default get_return_path function of iochannel does not work for
>> > RDMA live migration. So add the interface to set get_return_path.
>> >
>> > Signed-off-by: Lidong Chen <lidongchen@tencent.com>
>>
>> Lets see how Dan wants this done, he knows the channel/file stuff;
>> to me this feels like it should be adding a member to QIOChannelClass
>> that gets used by QEMUFile's get_return_path.
>
> No that doesn't really fit the model. IMHO the entire concept of a separate
> return path object is really wrong. The QIOChannel implementations are
> (almost) all capable of bi-directional I/O, which is why the the get_retun_path
> function just creates a second QEMUFile pointing to the same QIOChannel
> object we already had. Migration only needs the second QEMUFile, because that
> struct re-uses the same struct fields for tracking different bits of info
> depending on which direction you're doing I/O in. A real fix would be to
> stop overloading the same fields for multiple purposes in the QEMUFile, so
> that we only needed a single QEMUFile instance.
>
> Ignoring that though, the particular problem we're facing here is that the
> QIOChannelRDMA impl that is used is not written in a way that allows
> bi-directional I/O, despite the RDMA code it uses being capable of it.
>
> So rather than changing this get_return_path code, IMHO, the right fix to
> simply improve the QIOChannelRDMA impl so that it fully supports bi-directional
> I/O like all the other channels do.

Hi Daniel:
     Thanks for your suggestion.
     I will have a try.

>
> 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 :|

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