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David Alan Gilbert" , Leonardo Bras Soares Passos , Manish Mishra , peterx@redhat.com, Juan Quintela , "Daniel P . Berrange" Subject: [PATCH v9 01/14] migration: Add postcopy-preempt capability Date: Thu, 7 Jul 2022 14:53:29 -0400 Message-Id: <20220707185342.26794-2-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220707185342.26794-1-peterx@redhat.com> References: <20220707185342.26794-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1657220332951100001 Content-Type: text/plain; charset="utf-8" Firstly, postcopy already preempts precopy due to the fact that we do unqueue_page() first before looking into dirty bits. However that's not enough, e.g., when there're host huge page enabled, when sending a precopy huge page, a postcopy request needs to wait until the who= le huge page that is sending to finish. That could introduce quite some delay, the bigger the huge page is the larger delay it'll bring. This patch adds a new capability to allow postcopy requests to preempt exis= ting precopy page during sending a huge page, so that postcopy requests can be serviced even faster. Meanwhile to send it even faster, bypass the precopy stream by providing a standalone postcopy socket for sending requested pages. Since the new behavior will not be compatible with the old behavior, this w= ill not be the default, it's enabled only when the new capability is set on both src/dst QEMUs. This patch only adds the capability itself, the logic will be added in foll= ow up patches. Reviewed-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Signed-off-by: Peter Xu --- migration/migration.c | 18 ++++++++++++++++++ migration/migration.h | 1 + qapi/migration.json | 7 ++++++- 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/migration/migration.c b/migration/migration.c index 78f5057373..ce7bb68cdc 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1297,6 +1297,13 @@ static bool migrate_caps_check(bool *cap_list, return false; } =20 + if (cap_list[MIGRATION_CAPABILITY_POSTCOPY_PREEMPT]) { + if (!cap_list[MIGRATION_CAPABILITY_POSTCOPY_RAM]) { + error_setg(errp, "Postcopy preempt requires postcopy-ram"); + return false; + } + } + return true; } =20 @@ -2663,6 +2670,15 @@ bool migrate_background_snapshot(void) return s->enabled_capabilities[MIGRATION_CAPABILITY_BACKGROUND_SNAPSHO= T]; } =20 +bool migrate_postcopy_preempt(void) +{ + MigrationState *s; + + s =3D migrate_get_current(); + + return s->enabled_capabilities[MIGRATION_CAPABILITY_POSTCOPY_PREEMPT]; +} + /* migration thread support */ /* * Something bad happened to the RP stream, mark an error @@ -4274,6 +4290,8 @@ static Property migration_properties[] =3D { DEFINE_PROP_MIG_CAP("x-compress", MIGRATION_CAPABILITY_COMPRESS), DEFINE_PROP_MIG_CAP("x-events", MIGRATION_CAPABILITY_EVENTS), DEFINE_PROP_MIG_CAP("x-postcopy-ram", MIGRATION_CAPABILITY_POSTCOPY_RA= M), + DEFINE_PROP_MIG_CAP("x-postcopy-preempt", + MIGRATION_CAPABILITY_POSTCOPY_PREEMPT), DEFINE_PROP_MIG_CAP("x-colo", MIGRATION_CAPABILITY_X_COLO), DEFINE_PROP_MIG_CAP("x-release-ram", MIGRATION_CAPABILITY_RELEASE_RAM), DEFINE_PROP_MIG_CAP("x-block", MIGRATION_CAPABILITY_BLOCK), diff --git a/migration/migration.h b/migration/migration.h index 485d58b95f..d2269c826c 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -400,6 +400,7 @@ int migrate_decompress_threads(void); bool migrate_use_events(void); bool migrate_postcopy_blocktime(void); bool migrate_background_snapshot(void); +bool migrate_postcopy_preempt(void); =20 /* Sending on the return path - generic and then for each message type */ void migrate_send_rp_shut(MigrationIncomingState *mis, diff --git a/qapi/migration.json b/qapi/migration.json index 7102e474a6..7c60917675 100644 --- a/qapi/migration.json +++ b/qapi/migration.json @@ -467,6 +467,11 @@ # Requires that QEMU be permitted to use locked memory # for guest RAM pages. # (since 7.1) +# @postcopy-preempt: If enabled, the migration process will allow postcopy +# requests to preempt precopy stream, so postcopy reque= sts +# will be handled faster. This is a performance featur= e and +# should not affect the correctness of postcopy migrati= on. +# (since 7.1) # # Features: # @unstable: Members @x-colo and @x-ignore-shared are experimental. @@ -482,7 +487,7 @@ 'dirty-bitmaps', 'postcopy-blocktime', 'late-block-activate', { 'name': 'x-ignore-shared', 'features': [ 'unstable' ] }, 'validate-uuid', 'background-snapshot', - 'zero-copy-send'] } + 'zero-copy-send', 'postcopy-preempt'] } =20 ## # @MigrationCapabilityStatus: --=20 2.32.0