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Tue, 14 May 2024 17:57:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id Bs+TEgCmQ2azeAAAD6G6ig (envelope-from ); Tue, 14 May 2024 17:57:20 +0000 From: Fabiano Rosas To: Markus Armbruster , Peter Xu Cc: qemu-devel@nongnu.org, berrange@redhat.com, armbru@redhat.com, Claudio Fontana , Jim Fehlig , Eric Blake Subject: Re: [PATCH 4/9] migration: Add direct-io parameter In-Reply-To: <87ttj0zdp0.fsf@pond.sub.org> References: <20240426142042.14573-1-farosas@suse.de> <20240426142042.14573-5-farosas@suse.de> <871q6ioc2r.fsf@suse.de> <87ttj0zdp0.fsf@pond.sub.org> Date: Tue, 14 May 2024 14:57:18 -0300 Message-ID: <87r0e4e0ox.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.994]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_SEVEN(0.00)[8]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,suse.de:email] Received-SPF: pass client-ip=195.135.223.131; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Markus Armbruster writes: > Peter Xu writes: > >> On Fri, May 03, 2024 at 05:49:32PM -0300, Fabiano Rosas wrote: >>> Peter Xu writes: >>> >>> > 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"); >>> >> + } >>> > >>> > This will be the first parameter to optionally display here. I think it's >>> > a sign of misuse of has_direct_io field.. > > Yes. For similar existing parameters, we do > > assert(params->has_FOO); > monitor_printf(mon, "%s: '%s'\n", > MigrationParameter_str(MIGRATION_PARAMETER_FOO), > ... params->FOO as string ...) > >>> > IMHO has_direct_io should be best to be kept as "whether direct_io field is >>> > valid" and that's all of it. It hopefully shouldn't contain more >>> > information than that, or otherwise it'll be another small challenge we >>> > need to overcome when we can remove all these has_* fields, and can also be >>> > easily overlooked. >>> >>> I don't think I understand why we have those has_* fields. I thought my >>> usage of 'params->has_direct_io = qemu_has_direct_io()' was the correct >>> one, i.e. checking whether QEMU has any support for that parameter. Can >>> you help me out here? >> >> Here params is the pointer to "struct MigrationParameters", which is >> defined in qapi/migration.json. And we have had "has_*" only because we >> allow optional fields with asterisks: >> >> { 'struct': 'MigrationParameters', >> 'data': { '*announce-initial': 'size', >> ... >> } } >> >> So that's why it better only means "whether this field existed", because >> it's how it is defined. >> >> IIRC we (or say, Markus) used to have some attempts deduplicates those >> *MigrationParameter* things, and if success we have chance to drop has_* >> fields (in which case we simply always have them; that "has_" makes more >> sense only if in a QMP session to allow user only specify one or more >> things if not all). > > qapi/migration.json: > > ## > # @MigrationParameters: > # > --> # The optional members aren't actually optional. > # > > In other words, the has_FOO generated for the members of > MigrationParameters must all be true. > > These members became optional when we attempted to de-duplicate > MigrationParameters and MigrateSetParameters, but failed (see commit > de63ab61241 "migrate: Share common MigrationParameters struct" and > commit 1bda8b3c695 "migration: Unshare MigrationParameters struct for > now"). So what's the blocker for merging MigrationSetParameters and MigrationParameters? Just the tls_* options?