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Wed, 8 May 2024 08:25:36 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EF3B749104B; Wed, 8 May 2024 08:25:34 +0000 (UTC) Date: Wed, 8 May 2024 09:25:33 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Fabiano Rosas Cc: qemu-devel@nongnu.org, armbru@redhat.com, Peter Xu , Claudio Fontana , Jim Fehlig , Eric Blake Subject: Re: [PATCH 4/9] migration: Add direct-io parameter Message-ID: References: <20240426142042.14573-1-farosas@suse.de> <20240426142042.14573-5-farosas@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240426142042.14573-5-farosas@suse.de> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.581, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Apr 26, 2024 at 11:20:37AM -0300, Fabiano Rosas wrote: > Add the direct-io migration parameter that tells the migration code to > use O_DIRECT when opening the migration stream file whenever possible. > > This is currently only used with the mapped-ram migration that has a > clear window guaranteed to perform aligned writes. > > Acked-by: Markus Armbruster > Signed-off-by: Fabiano Rosas > --- > include/qemu/osdep.h | 2 ++ > migration/migration-hmp-cmds.c | 11 +++++++++++ > migration/options.c | 30 ++++++++++++++++++++++++++++++ > migration/options.h | 1 + > qapi/migration.json | 18 +++++++++++++++--- > util/osdep.c | 9 +++++++++ > 6 files changed, 68 insertions(+), 3 deletions(-) > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index c7053cdc2b..645c14a65d 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -612,6 +612,8 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive); > bool qemu_has_ofd_lock(void); > #endif > > +bool qemu_has_direct_io(void); > + > #if defined(__HAIKU__) && defined(__i386__) > #define FMT_pid "%ld" > #elif defined(WIN64) > diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c > index 7e96ae6ffd..8496a2b34e 100644 > --- a/migration/migration-hmp-cmds.c > +++ b/migration/migration-hmp-cmds.c > @@ -397,6 +397,13 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict) > monitor_printf(mon, "%s: %s\n", > MigrationParameter_str(MIGRATION_PARAMETER_MODE), > qapi_enum_lookup(&MigMode_lookup, params->mode)); > + > + if (params->has_direct_io) { > + monitor_printf(mon, "%s: %s\n", > + MigrationParameter_str( > + MIGRATION_PARAMETER_DIRECT_IO), > + params->direct_io ? "on" : "off"); > + } > } > > qapi_free_MigrationParameters(params); > @@ -690,6 +697,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict) > p->has_mode = true; > visit_type_MigMode(v, param, &p->mode, &err); > break; > + case MIGRATION_PARAMETER_DIRECT_IO: > + p->has_direct_io = true; > + visit_type_bool(v, param, &p->direct_io, &err); > + break; > default: > assert(0); > } > diff --git a/migration/options.c b/migration/options.c > index 239f5ecfb4..ae464aa4f2 100644 > --- a/migration/options.c > +++ b/migration/options.c > @@ -826,6 +826,22 @@ int migrate_decompress_threads(void) > return s->parameters.decompress_threads; > } > > +bool migrate_direct_io(void) > +{ > + MigrationState *s = migrate_get_current(); > + > + /* For now O_DIRECT is only supported with mapped-ram */ > + if (!s->capabilities[MIGRATION_CAPABILITY_MAPPED_RAM]) { > + return false; > + } > + > + if (s->parameters.has_direct_io) { > + return s->parameters.direct_io; > + } > + > + return false; > +} > + > uint64_t migrate_downtime_limit(void) > { > MigrationState *s = migrate_get_current(); > @@ -1061,6 +1077,11 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp) > params->has_zero_page_detection = true; > params->zero_page_detection = s->parameters.zero_page_detection; > > + if (s->parameters.has_direct_io) { > + params->has_direct_io = true; > + params->direct_io = s->parameters.direct_io; > + } > + > return params; > } > > @@ -1097,6 +1118,7 @@ void migrate_params_init(MigrationParameters *params) > params->has_vcpu_dirty_limit = true; > params->has_mode = true; > params->has_zero_page_detection = true; > + params->has_direct_io = qemu_has_direct_io(); > } > > /* > @@ -1416,6 +1438,10 @@ static void migrate_params_test_apply(MigrateSetParameters *params, > if (params->has_zero_page_detection) { > dest->zero_page_detection = params->zero_page_detection; > } > + > + if (params->has_direct_io) { > + dest->direct_io = params->direct_io; > + } > } > > static void migrate_params_apply(MigrateSetParameters *params, Error **errp) > @@ -1570,6 +1596,10 @@ 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->has_direct_io) { > + s->parameters.direct_io = params->direct_io; > + } > } I would expect to see something added to migrat_params_check() that calls qemu_has_direct_io() and reports an error if the platform lacks O_DIRECT, so mgmt apps see when they're trying to use O_DIRECT on a bad platform straightaway, rather than only when migration starts later. Alternatively, and perhaps better would be for use to have a meson.build check for O_DIRECT, and then make all the QAPI features have a condition on CONFIG_O_DIRECT, so QAPI rejects any use of 'direct-io' feature at input time. 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 :|