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bh=cp4T0OV/eWxNPPdn5wej7DTuu59xZM6LTLe/vHPYQB0=; b=JHybcuBgEmNvr9CQ1cEBE3C7R885W007G45WAd+2iGVM2qNA+psIwQxy2Z2UDuVWcEIik+ Nms3oSckHQG2nKagQetc5eJbaw1PpR8TsvOWr7gKjB99iJwjNVy2kdqpq1XBPHAso+k2XZ T2+AaxDBCv068pFUIn+ToopWIDNTM+A= X-MC-Unique: VsZeWIjlOD2A3XRwGzkBXA-1 From: peterx@redhat.com To: Peter Maydell , qemu-devel@nongnu.org Cc: peterx@redhat.com, Fabiano Rosas Subject: [PULL 15/34] migration/multifd: Forbid spurious wakeups Date: Thu, 8 Feb 2024 11:05:09 +0800 Message-ID: <20240208030528.368214-16-peterx@redhat.com> In-Reply-To: <20240208030528.368214-1-peterx@redhat.com> References: <20240208030528.368214-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.106, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1707361746089100001 Content-Type: text/plain; charset="utf-8" From: Peter Xu Now multifd's logic is designed to have no spurious wakeup. I still remember a talk to Juan and he seems to agree we should drop it now, and if my memory was right it was there because multifd used to hit that when still debugging. Let's drop it and see what can explode; as long as it's not reaching soft-freeze. Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/r/20240202102857.110210-15-peterx@redhat.com Signed-off-by: Peter Xu --- migration/multifd.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/migration/multifd.c b/migration/multifd.c index 6aa44340de..28b54100cd 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -756,7 +756,9 @@ static void *multifd_send_thread(void *opaque) p->next_packet_size =3D 0; qatomic_set(&p->pending_job, false); qemu_mutex_unlock(&p->mutex); - } else if (qatomic_read(&p->pending_sync)) { + } else { + /* If not a normal job, must be a sync request */ + assert(qatomic_read(&p->pending_sync)); p->flags =3D MULTIFD_FLAG_SYNC; multifd_send_fill_packet(p); ret =3D qio_channel_write_all(p->c, (void *)p->packet, @@ -771,9 +773,6 @@ static void *multifd_send_thread(void *opaque) qatomic_set(&p->pending_sync, false); qemu_mutex_unlock(&p->mutex); qemu_sem_post(&p->sem_sync); - } else { - qemu_mutex_unlock(&p->mutex); - /* sometimes there are spurious wakeups */ } } =20 --=20 2.43.0