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Szmigiero" Subject: Re: [RFC PATCH 6/7] migration/multifd: Move payload storage out of the channel parameters In-Reply-To: References: <20240620212111.29319-7-farosas@suse.de> <877cdtfcsi.fsf@suse.de> <87y169dmu3.fsf@suse.de> <87msmodnly.fsf@suse.de> <87jzhi1odn.fsf@suse.de> Date: Thu, 18 Jul 2024 18:27:32 -0300 Message-ID: <87frs61jcr.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-0.30 / 50.00]; NEURAL_HAM_SHORT(-0.20)[-0.995]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; MISSING_XM_UA(0.00)[]; TO_DN_SOME(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_THREE(0.00)[4]; MID_RHS_MATCH_FROM(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo] Received-SPF: pass client-ip=195.135.223.130; envelope-from=farosas@suse.de; helo=smtp-out1.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 Peter Xu writes: > On Thu, Jul 18, 2024 at 04:39:00PM -0300, Fabiano Rosas wrote: >> v2 is ready, but unfortunately this approach doesn't work. When client A >> takes the payload, it fills it with it's data, which may include >> allocating memory. MultiFDPages_t does that for the offset. This means >> we need a round of free/malloc at every packet sent. For every client >> and every allocation they decide to do. > > Shouldn't be a blocker? E.g. one option is: > > /* Allocate both the pages + offset[] */ > MultiFDPages_t *pages = g_malloc0(sizeof(MultiFDPages_t) + > sizeof(ram_addr_t) * n, 1); > pages->allocated = n; > pages->offset = &pages[1]; > > Or.. we can also make offset[] dynamic size, if that looks less tricky: > > typedef struct { > /* number of used pages */ > uint32_t num; > /* number of normal pages */ > uint32_t normal_num; > /* number of allocated pages */ > uint32_t allocated; > RAMBlock *block; > /* offset of each page */ > ram_addr_t offset[0]; > } MultiFDPages_t; I think you missed the point. If we hold a pointer inside the payload, we lose the reference when the other client takes the structure and puts its own data there. So we'll need to alloc/free everytime we send a packet.