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Mon, 18 May 2026 20:21:19 +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 3Cf6Ib90C2o2WQAAD6G6ig (envelope-from ); Mon, 18 May 2026 20:21:19 +0000 From: Fabiano Rosas To: Bin Guo , qemu-devel@nongnu.org Cc: peterx@redhat.com Subject: Re: [PATCH 6/8] migration/multifd: merge thread-join and cleanup loops in multifd_recv_cleanup In-Reply-To: <20260518110112.21395-7-guobin@linux.alibaba.com> References: <20260518110112.21395-1-guobin@linux.alibaba.com> <20260518110112.21395-7-guobin@linux.alibaba.com> Date: Mon, 18 May 2026 17:21:17 -0300 Message-ID: <87bjec4gg2.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_VIA_SMTP_AUTH(0.00)[]; TO_DN_SOME(0.00)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; 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, suse.de:mid, alibaba.com:email] 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: qemu development 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 Bin Guo writes: > multifd_recv_cleanup() iterates over all receive channels twice: > one loop to join threads and another to clean up each channel. ok > Unlike the send side where all threads must be signalled before any is > joined (to avoid deadlock), Not super relevant what the send side does. It's just a similar piece of code, that's all. > on the receive side the threads are already > terminated by multifd_recv_terminate_threads(). Each join simply > waits for an already-terminated thread, so the join and cleanup for > channel i are independent of channel j, and the two loops can safely > be merged into one. > We do really need to join all threads before proceeding. There's no guarantee on the the order in which they'll terminate. > This cuts the iteration count in half and improves locality: the > thread's resources are freed immediately after its join. > > Signed-off-by: Bin Guo > --- > migration/multifd.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/migration/multifd.c b/migration/multifd.c > index b3eef875cc..67ee9bdf5e 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -1153,15 +1153,14 @@ void multifd_recv_cleanup(void) > return; > } > multifd_recv_terminate_threads(NULL); > + > for (i = 0; i < migrate_multifd_channels(); i++) { > MultiFDRecvParams *p = &multifd_recv_state->params[i]; > > if (p->thread_created) { > qemu_thread_join(&p->thread); > } > - } > - for (i = 0; i < migrate_multifd_channels(); i++) { > - multifd_recv_cleanup_channel(&multifd_recv_state->params[i]); > + multifd_recv_cleanup_channel(p); > } > multifd_recv_cleanup_state(); > }