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Fri, 2 Feb 2024 19:23:18 +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 /hC2NSZBvWUJZwAAD6G6ig (envelope-from ); Fri, 02 Feb 2024 19:23:18 +0000 From: Fabiano Rosas To: peterx@redhat.com, qemu-devel@nongnu.org Cc: Hao Xiang , Bryan Zhang , peterx@redhat.com, Avihai Horon , Yuan Liu , Prasad Pandit Subject: Re: [PATCH v2 07/23] migration/multifd: Simplify locking in sender thread In-Reply-To: <20240202102857.110210-8-peterx@redhat.com> References: <20240202102857.110210-1-peterx@redhat.com> <20240202102857.110210-8-peterx@redhat.com> Date: Fri, 02 Feb 2024 16:23:16 -0300 Message-ID: <87r0huhdqz.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [-0.10 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; URIBL_BLOCKED(0.00)[suse.de:email]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BAYES_HAM(-0.00)[35.38%]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_SEVEN(0.00)[8]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:1; 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, 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org peterx@redhat.com writes: > From: Peter Xu > > The sender thread will yield the p->mutex before IO starts, trying to not > block the requester thread. This may be unnecessary lock optimizations, > because the requester can already read pending_job safely even without the > lock, because the requester is currently the only one who can assign a > task. > > Drop that lock complication on both sides: > > (1) in the sender thread, always take the mutex until job done > (2) in the requester thread, check pending_job clear lockless > > Signed-off-by: Peter Xu Reviewed-by: Fabiano Rosas