diff mbox series

[v4,08/14] migration/multifd: Add new migration option for multifd DSA offloading.

Message ID 20240425022117.4035031-9-hao.xiang@linux.dev (mailing list archive)
State New, archived
Headers show
Series Use Intel DSA accelerator to offload zero page checking in multifd live migration. | expand

Commit Message

Hao Xiang April 25, 2024, 2:21 a.m. UTC 
Intel DSA offloading is an optional feature that turns on if
proper hardware and software stack is available. To turn on
DSA offloading in multifd live migration:

multifd-dsa-accel="[dsa_dev_path1] [dsa_dev_path2] ... [dsa_dev_pathX]"

This feature is turned off by default.

Signed-off-by: Hao Xiang <hao.xiang@linux.dev>
---
 migration/migration-hmp-cmds.c |  8 ++++++++
 migration/options.c            | 30 ++++++++++++++++++++++++++++++
 migration/options.h            |  1 +
 qapi/migration.json            | 26 +++++++++++++++++++++++---
 4 files changed, 62 insertions(+), 3 deletions(-)

Comments

Daniel P. Berrangé April 25, 2024, 2:17 p.m. UTC | #1 
On Thu, Apr 25, 2024 at 02:21:11AM +0000, Hao Xiang wrote:
> Intel DSA offloading is an optional feature that turns on if
> proper hardware and software stack is available. To turn on
> DSA offloading in multifd live migration:
> 
> multifd-dsa-accel="[dsa_dev_path1] [dsa_dev_path2] ... [dsa_dev_pathX]"
> 
> This feature is turned off by default.
> 
> Signed-off-by: Hao Xiang <hao.xiang@linux.dev>
> ---
>  migration/migration-hmp-cmds.c |  8 ++++++++
>  migration/options.c            | 30 ++++++++++++++++++++++++++++++
>  migration/options.h            |  1 +
>  qapi/migration.json            | 26 +++++++++++++++++++++++---
>  4 files changed, 62 insertions(+), 3 deletions(-)

> diff --git a/qapi/migration.json b/qapi/migration.json
> index 8c65b90328..934fa8839e 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -914,6 +914,12 @@
>  #     See description in @ZeroPageDetection.  Default is 'multifd'.
>  #     (since 9.0)
>  #
> +# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
> +#     certain memory operations. Enable DSA accelerator offloading by
> +#     setting this string to a list of DSA device path separated by space
> +#     characters. Setting this string to an empty string means disabling
> +#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)

Passing a list of paths as a single space separate string is a
design anti-pattern. This needs to use a list type at the QAPI
level.

Also I don't think we need add 'multifd' on the name - all
new features are for multifd.

Overall it should be called 'dsa-accel-path' I thjink

> @@ -1122,6 +1128,12 @@
>  #     See description in @ZeroPageDetection.  Default is 'multifd'.
>  #     (since 9.0)
>  #
> +# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
> +#     certain memory operations. Enable DSA accelerator offloading by
> +#     setting this string to a list of DSA device path separated by space
> +#     characters. Setting this string to an empty string means disabling
> +#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)
> +#
>  # Features:
>  #
>  # @deprecated: Member @block-incremental is deprecated.  Use
> @@ -1176,7 +1188,8 @@
>                                              'features': [ 'unstable' ] },
>              '*vcpu-dirty-limit': 'uint64',
>              '*mode': 'MigMode',
> -            '*zero-page-detection': 'ZeroPageDetection'} }
> +            '*zero-page-detection': 'ZeroPageDetection',
> +            '*multifd-dsa-accel': 'StrOrNull'} }

This needs to be

  ['str']   not 'StrOrNull'

>  
>  ##
>  # @migrate-set-parameters:
> @@ -1354,6 +1367,12 @@
>  #     See description in @ZeroPageDetection.  Default is 'multifd'.
>  #     (since 9.0)
>  #
> +# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
> +#     certain memory operations. Enable DSA accelerator offloading by
> +#     setting this string to a list of DSA device path separated by space
> +#     characters. Setting this string to an empty string means disabling
> +#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)
> +#
>  # Features:
>  #
>  # @deprecated: Member @block-incremental is deprecated.  Use
> @@ -1405,7 +1424,8 @@
>                                              'features': [ 'unstable' ] },
>              '*vcpu-dirty-limit': 'uint64',
>              '*mode': 'MigMode',
> -            '*zero-page-detection': 'ZeroPageDetection'} }
> +            '*zero-page-detection': 'ZeroPageDetection',
> +            '*multifd-dsa-accel': 'str'} }

Liekewise needs to be

   ['str']


Having mgmt apps pass in the path every time though, feels like
overkill. Surely there's a standard path that QEMU should use
by default, and should only require flag to turn on its usage.

IOW, why not extend the ZeroPageDetection enum, to have a further
entry for 'dsa' to request ue of dsa accel. Passing paths could
be optional.


With regards,
Daniel
Markus Armbruster April 26, 2024, 9:16 a.m. UTC | #2 
Daniel P. Berrangé <berrange@redhat.com> writes:

> On Thu, Apr 25, 2024 at 02:21:11AM +0000, Hao Xiang wrote:
>> Intel DSA offloading is an optional feature that turns on if
>> proper hardware and software stack is available. To turn on
>> DSA offloading in multifd live migration:
>> 
>> multifd-dsa-accel="[dsa_dev_path1] [dsa_dev_path2] ... [dsa_dev_pathX]"
>> 
>> This feature is turned off by default.
>> 
>> Signed-off-by: Hao Xiang <hao.xiang@linux.dev>
>> ---
>>  migration/migration-hmp-cmds.c |  8 ++++++++
>>  migration/options.c            | 30 ++++++++++++++++++++++++++++++
>>  migration/options.h            |  1 +
>>  qapi/migration.json            | 26 +++++++++++++++++++++++---
>>  4 files changed, 62 insertions(+), 3 deletions(-)
>
>> diff --git a/qapi/migration.json b/qapi/migration.json
>> index 8c65b90328..934fa8839e 100644
>> --- a/qapi/migration.json
>> +++ b/qapi/migration.json
>> @@ -914,6 +914,12 @@
>>  #     See description in @ZeroPageDetection.  Default is 'multifd'.
>>  #     (since 9.0)
>>  #
>> +# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
>> +#     certain memory operations. Enable DSA accelerator offloading by
>> +#     setting this string to a list of DSA device path separated by space
>> +#     characters. Setting this string to an empty string means disabling
>> +#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)
>
> Passing a list of paths as a single space separate string is a
> design anti-pattern. This needs to use a list type at the QAPI
> level.

Yup.

> Also I don't think we need add 'multifd' on the name - all
> new features are for multifd.
>
> Overall it should be called 'dsa-accel-path' I thjink

Moreover, docs/devel/qapi-code-gen.rst:

    For legibility, wrap text paragraphs so every line is at most 70
    characters long.

    Separate sentences with two spaces.

[...]
diff mbox series

Patch

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 7e96ae6ffd..7e9bb278c9 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -358,6 +358,9 @@  void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
         monitor_printf(mon, "%s: '%s'\n",
             MigrationParameter_str(MIGRATION_PARAMETER_TLS_AUTHZ),
             params->tls_authz);
+        monitor_printf(mon, "%s: '%s'\n",
+            MigrationParameter_str(MIGRATION_PARAMETER_MULTIFD_DSA_ACCEL),
+            params->multifd_dsa_accel);
 
         if (params->has_block_bitmap_mapping) {
             const BitmapMigrationNodeAliasList *bmnal;
@@ -622,6 +625,11 @@  void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
         p->has_block_incremental = true;
         visit_type_bool(v, param, &p->block_incremental, &err);
         break;
+    case MIGRATION_PARAMETER_MULTIFD_DSA_ACCEL:
+        p->multifd_dsa_accel = g_new0(StrOrNull, 1);
+        p->multifd_dsa_accel->type = QTYPE_QSTRING;
+        visit_type_str(v, param, &p->multifd_dsa_accel->u.s, &err);
+        break;
     case MIGRATION_PARAMETER_MULTIFD_CHANNELS:
         p->has_multifd_channels = true;
         visit_type_uint8(v, param, &p->multifd_channels, &err);
diff --git a/migration/options.c b/migration/options.c
index 239f5ecfb4..dc8642df81 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -182,6 +182,8 @@  Property migration_properties[] = {
     DEFINE_PROP_ZERO_PAGE_DETECTION("zero-page-detection", MigrationState,
                        parameters.zero_page_detection,
                        ZERO_PAGE_DETECTION_MULTIFD),
+    DEFINE_PROP_STRING("multifd-dsa-accel", MigrationState,
+                       parameters.multifd_dsa_accel),
 
     /* Migration capabilities */
     DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -920,6 +922,13 @@  const char *migrate_tls_creds(void)
     return s->parameters.tls_creds;
 }
 
+const char *migrate_multifd_dsa_accel(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return s->parameters.multifd_dsa_accel;
+}
+
 const char *migrate_tls_hostname(void)
 {
     MigrationState *s = migrate_get_current();
@@ -1060,6 +1069,8 @@  MigrationParameters *qmp_query_migrate_parameters(Error **errp)
     params->mode = s->parameters.mode;
     params->has_zero_page_detection = true;
     params->zero_page_detection = s->parameters.zero_page_detection;
+    params->multifd_dsa_accel = g_strdup(s->parameters.multifd_dsa_accel ?
+                                         s->parameters.multifd_dsa_accel : "");
 
     return params;
 }
@@ -1068,6 +1079,7 @@  void migrate_params_init(MigrationParameters *params)
 {
     params->tls_hostname = g_strdup("");
     params->tls_creds = g_strdup("");
+    params->multifd_dsa_accel = g_strdup("");
 
     /* Set has_* up only for parameter checks */
     params->has_compress_level = true;
@@ -1416,6 +1428,11 @@  static void migrate_params_test_apply(MigrateSetParameters *params,
     if (params->has_zero_page_detection) {
         dest->zero_page_detection = params->zero_page_detection;
     }
+
+    if (params->multifd_dsa_accel) {
+        assert(params->multifd_dsa_accel->type == QTYPE_QSTRING);
+        dest->multifd_dsa_accel = params->multifd_dsa_accel->u.s;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1570,6 +1587,13 @@  static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
     if (params->has_zero_page_detection) {
         s->parameters.zero_page_detection = params->zero_page_detection;
     }
+
+    if (params->multifd_dsa_accel) {
+        g_free(s->parameters.multifd_dsa_accel);
+        assert(params->multifd_dsa_accel->type == QTYPE_QSTRING);
+        s->parameters.multifd_dsa_accel =
+            g_strdup(params->multifd_dsa_accel->u.s);
+    }
 }
 
 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
@@ -1595,6 +1619,12 @@  void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
         params->tls_authz->type = QTYPE_QSTRING;
         params->tls_authz->u.s = strdup("");
     }
+    if (params->multifd_dsa_accel
+        && params->multifd_dsa_accel->type == QTYPE_QNULL) {
+        qobject_unref(params->multifd_dsa_accel->u.n);
+        params->multifd_dsa_accel->type = QTYPE_QSTRING;
+        params->multifd_dsa_accel->u.s = strdup("");
+    }
 
     migrate_params_test_apply(params, &tmp);
 
diff --git a/migration/options.h b/migration/options.h
index ab8199e207..1cb3393be9 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -91,6 +91,7 @@  const char *migrate_tls_creds(void);
 const char *migrate_tls_hostname(void);
 uint64_t migrate_xbzrle_cache_size(void);
 ZeroPageDetection migrate_zero_page_detection(void);
+const char *migrate_multifd_dsa_accel(void);
 
 /* parameters setters */
 
diff --git a/qapi/migration.json b/qapi/migration.json
index 8c65b90328..934fa8839e 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -914,6 +914,12 @@ 
 #     See description in @ZeroPageDetection.  Default is 'multifd'.
 #     (since 9.0)
 #
+# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
+#     certain memory operations. Enable DSA accelerator offloading by
+#     setting this string to a list of DSA device path separated by space
+#     characters. Setting this string to an empty string means disabling
+#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -937,7 +943,7 @@ 
            'cpu-throttle-initial', 'cpu-throttle-increment',
            'cpu-throttle-tailslow',
            'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
-           'avail-switchover-bandwidth', 'downtime-limit',
+           'avail-switchover-bandwidth', 'downtime-limit', 'multifd-dsa-accel',
            { 'name': 'x-checkpoint-delay', 'features': [ 'unstable' ] },
            { 'name': 'block-incremental', 'features': [ 'deprecated' ] },
            'multifd-channels',
@@ -1122,6 +1128,12 @@ 
 #     See description in @ZeroPageDetection.  Default is 'multifd'.
 #     (since 9.0)
 #
+# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
+#     certain memory operations. Enable DSA accelerator offloading by
+#     setting this string to a list of DSA device path separated by space
+#     characters. Setting this string to an empty string means disabling
+#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -1176,7 +1188,8 @@ 
                                             'features': [ 'unstable' ] },
             '*vcpu-dirty-limit': 'uint64',
             '*mode': 'MigMode',
-            '*zero-page-detection': 'ZeroPageDetection'} }
+            '*zero-page-detection': 'ZeroPageDetection',
+            '*multifd-dsa-accel': 'StrOrNull'} }
 
 ##
 # @migrate-set-parameters:
@@ -1354,6 +1367,12 @@ 
 #     See description in @ZeroPageDetection.  Default is 'multifd'.
 #     (since 9.0)
 #
+# @multifd-dsa-accel: If enabled, use DSA accelerator offloading for
+#     certain memory operations. Enable DSA accelerator offloading by
+#     setting this string to a list of DSA device path separated by space
+#     characters. Setting this string to an empty string means disabling
+#     DSA accelerator offloading. Defaults to an empty string. (since 9.2)
+#
 # Features:
 #
 # @deprecated: Member @block-incremental is deprecated.  Use
@@ -1405,7 +1424,8 @@ 
                                             'features': [ 'unstable' ] },
             '*vcpu-dirty-limit': 'uint64',
             '*mode': 'MigMode',
-            '*zero-page-detection': 'ZeroPageDetection'} }
+            '*zero-page-detection': 'ZeroPageDetection',
+            '*multifd-dsa-accel': 'str'} }
 
 ##
 # @query-migrate-parameters: