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(unknown [2a02:6bf:8080:a5d::1:36]) by mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id Nmd3dr0GuSw0-FxGAKwFt; Sun, 24 Aug 2025 00:48:28 +0300 Precedence: bulk X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1755985708; bh=zKfF0Jr3ZNXBdyUSBJ7GUqENZhLe0Y59SMSSlwzFldU=; h=Message-ID:Date:In-Reply-To:Cc:Subject:References:To:From; b=vBluVYAEm0HRd3eXs6En1RH0DMWTRMwRzrW7pYAxQShntPNs2wB6Hl7UIFZkGD2el StC9W1J51ZhHdPiGqQsSCbeiSR+vYP+MMJt15m5AdBPP4yYxz6Zwr2eUdOckcaQB/5 PwdK9FenW0WfZIULajAYlXRyk78RP07xahhNba/8= Authentication-Results: mail-nwsmtp-smtp-corp-main-34.sas.yp-c.yandex.net; dkim=pass header.i=@yandex-team.ru From: Vladimir Sementsov-Ogievskiy To: jasowang@redhat.com Cc: qemu-devel@nongnu.org, vsementsov@yandex-team.ru, leiyang@redhat.com, steven.sistare@oracle.com, peterx@redhat.com, mst@redhat.com, farosas@suse.de, yc-core@yandex-team.ru Subject: [RFC 6/7] net/tap: experimental support for vhost in local tap migration Date: Sun, 24 Aug 2025 00:48:20 +0300 Message-ID: <20250823214821.48342-7-vsementsov@yandex-team.ru> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250823214821.48342-1-vsementsov@yandex-team.ru> References: <20250823214821.48342-1-vsementsov@yandex-team.ru> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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=178.154.239.136; envelope-from=vsementsov@yandex-team.ru; helo=forwardcorp1b.mail.yandex.net X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, 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 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 @yandex-team.ru) X-ZM-MESSAGEID: 1755985760416116600 Content-Type: text/plain; charset="utf-8" Just reinitialize vhost after getting the fd on target. This significantly increase downtime (0.03s -> 0.06s in my simple testing). So next step is to rework it, completely migrating the vhost state to the new qemu without reinitialization. Signed-off-by: Vladimir Sementsov-Ogievskiy --- net/tap.c | 35 +++++++++++++++++------------------ 1 file changed, 17 insertions(+), 18 deletions(-) diff --git a/net/tap.c b/net/tap.c index 4d3cdc0662..7a4de07025 100644 --- a/net/tap.c +++ b/net/tap.c @@ -84,6 +84,9 @@ typedef struct TAPState { unsigned host_vnet_hdr_len; Notifier exit; bool local_incoming; + bool need_vhost; + char *vhost_fdname; + uint32_t vhost_busyloop_timeout; } TAPState; =20 static void launch_script(const char *setup_script, const char *ifname, @@ -98,8 +101,7 @@ static int net_tap_fd_init_common(const Netdev *netdev, = NetClientState *peer, const char *downscript, const char *vhostfdname, int vnet_hdr, int fd, Error **errp); -static int net_tap_setup_vhost(TAPState *s, const NetdevTapOptions *tap, - const char *vhostfdname, Error **errp); +static int net_tap_setup_vhost(TAPState *s, Error **errp); =20 static void tap_update_fd_handler(TAPState *s) { @@ -384,6 +386,7 @@ static void tap_cleanup(NetClientState *nc) g_free(s->vhost_net); s->vhost_net =3D NULL; } + g_free(s->vhost_fdname); =20 qemu_purge_queued_packets(nc); =20 @@ -794,10 +797,8 @@ int tap_load(NetClientState *nc, QEMUFile *f) qemu_get_be32s(f, &s->host_vnet_hdr_len); =20 tap_read_poll(s, true); - s->exit.notify =3D tap_exit_notify; - qemu_add_exit_notifier(&s->exit); =20 - return 0; + return net_tap_setup_vhost(s, NULL); } =20 static int net_tap_fd_init_common(const Netdev *netdev, NetClientState *pe= er, @@ -874,8 +875,12 @@ static int net_tap_fd_init_common(const Netdev *netdev= , NetClientState *peer, } } =20 + s->need_vhost =3D tap->has_vhost ? tap->vhost : + vhostfdname || (tap->has_vhostforce && tap->vhostforce); + s->vhost_fdname =3D g_strdup(vhostfdname); + s->vhost_busyloop_timeout =3D tap->has_poll_us ? tap->poll_us : 0; if (!local_incoming) { - ret =3D net_tap_setup_vhost(s, tap, vhostfdname, errp); + ret =3D net_tap_setup_vhost(s, errp); if (ret < 0) { goto failed; } @@ -888,28 +893,22 @@ failed: return -1; } =20 -static int net_tap_setup_vhost(TAPState *s, const NetdevTapOptions *tap, - const char *vhostfdname, Error **errp) +static int net_tap_setup_vhost(TAPState *s, Error **errp) { - if (tap->has_vhost ? tap->vhost : - vhostfdname || (tap->has_vhostforce && tap->vhostforce)) { + if (s->need_vhost) { VhostNetOptions options; int vhostfd; =20 options.backend_type =3D VHOST_BACKEND_TYPE_KERNEL; options.net_backend =3D &s->nc; - if (tap->has_poll_us) { - options.busyloop_timeout =3D tap->poll_us; - } else { - options.busyloop_timeout =3D 0; - } + options.busyloop_timeout =3D s->vhost_busyloop_timeout; =20 - if (vhostfdname) { - vhostfd =3D monitor_fd_param(monitor_cur(), vhostfdname, errp); + if (s->vhost_fdname) { + vhostfd =3D monitor_fd_param(monitor_cur(), s->vhost_fdname, e= rrp); if (vhostfd =3D=3D -1) { return -1; } - if (!set_fd_nonblocking(vhostfd, vhostfdname, errp)) { + if (!set_fd_nonblocking(vhostfd, s->vhost_fdname, errp)) { return -1; } } else { --=20 2.48.1