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Tsirkin" Cc: Shao-Chien Chiang , qemu-devel@nongnu.org Subject: [RFC PATCH v1 2/2] vhost-vdpa: cache device config Date: Tue, 18 Apr 2023 21:01:07 +0800 Message-Id: <5c10e79c26b8dda38ebeba6bcafb8bc650f6a588.1681819697.git.ray90514@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: References: 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=2607:f8b0:4864:20::62a; envelope-from=ray90514@gmail.com; helo=mail-pl1-x62a.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 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, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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-Mailman-Approved-At: Tue, 18 Apr 2023 09:21:36 -0400 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 @gmail.com) X-ZM-MESSAGEID: 1681824144551100001 Content-Type: text/plain; charset="utf-8" The config caching is disabled when starting config interruption. If we could know whether there is a config interruption, I think we can invalidate the cache at that time instead of disabling the caching mechanism.=20 After caching the device config, the latency is reduced by 0.066 sec. Signed-off-by: Shao-Chien Chiang --- hw/virtio/vhost-vdpa.c | 44 +++++++++++++++++++++++++++------- include/hw/virtio/vhost-vdpa.h | 2 ++ 2 files changed, 38 insertions(+), 8 deletions(-) diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c index ccde4c7040..92bb09ef4d 100644 --- a/hw/virtio/vhost-vdpa.c +++ b/hw/virtio/vhost-vdpa.c @@ -436,6 +436,8 @@ static int vhost_vdpa_init(struct vhost_dev *dev, void = *opaque, Error **errp) v->msg_type =3D VHOST_IOTLB_MSG_V2; v->status =3D 0; v->features =3D dev->features; + v->config =3D NULL; + v->config_cache_enabled =3D true; vhost_vdpa_init_svq(dev, v); =20 error_propagate(&dev->migration_blocker, v->migration_blocker); @@ -748,8 +750,16 @@ static int vhost_vdpa_set_vring_ready(struct vhost_dev= *dev) static int vhost_vdpa_set_config_call(struct vhost_dev *dev, int fd) { + struct vhost_vdpa *v =3D dev->opaque; + int ret; + trace_vhost_vdpa_set_config_call(dev, fd); - return vhost_vdpa_call(dev, VHOST_VDPA_SET_CONFIG_CALL, &fd); + ret =3D vhost_vdpa_call(dev, VHOST_VDPA_SET_CONFIG_CALL, &fd); + if (ret =3D=3D 0) { + v->config_cache_enabled =3D false; + } + + return ret; } =20 static void vhost_vdpa_dump_config(struct vhost_dev *dev, const uint8_t *c= onfig, @@ -769,6 +779,7 @@ static int vhost_vdpa_set_config(struct vhost_dev *dev,= const uint8_t *data, uint32_t offset, uint32_t size, uint32_t flags) { + struct vhost_vdpa *v =3D dev->opaque; struct vhost_vdpa_config *config; int ret; unsigned long config_size =3D offsetof(struct vhost_vdpa_config, buf); @@ -783,6 +794,11 @@ static int vhost_vdpa_set_config(struct vhost_dev *dev= , const uint8_t *data, vhost_vdpa_dump_config(dev, data, size); } ret =3D vhost_vdpa_call(dev, VHOST_VDPA_SET_CONFIG, config); + if (v->config_cache_enabled && v->config !=3D NULL) { + if (ret =3D=3D 0) { + memcpy(v->config->buf + offset, data, size); + } + } g_free(config); return ret; } @@ -790,17 +806,29 @@ static int vhost_vdpa_set_config(struct vhost_dev *de= v, const uint8_t *data, static int vhost_vdpa_get_config(struct vhost_dev *dev, uint8_t *config, uint32_t config_len, Error **errp) { - struct vhost_vdpa_config *v_config; + struct vhost_vdpa *v =3D dev->opaque; unsigned long config_size =3D offsetof(struct vhost_vdpa_config, buf); int ret; =20 trace_vhost_vdpa_get_config(dev, config, config_len); - v_config =3D g_malloc(config_len + config_size); - v_config->len =3D config_len; - v_config->off =3D 0; - ret =3D vhost_vdpa_call(dev, VHOST_VDPA_GET_CONFIG, v_config); - memcpy(config, v_config->buf, config_len); - g_free(v_config); + if (v->config_cache_enabled && v->config !=3D NULL) { + if (config_len <=3D v->config->len) { + memcpy(config, v->config->buf, config_len); + ret =3D 0; + } else { + ret =3D -EINVAL; + } + } else { + v->config =3D g_malloc(config_len + config_size); + v->config->len =3D config_len; + v->config->off =3D 0; + ret =3D vhost_vdpa_call(dev, VHOST_VDPA_GET_CONFIG, v->config); + memcpy(config, v->config->buf, config_len); + if (!v->config_cache_enabled) { + g_free(v->config); + v->config =3D NULL; + } + } if (trace_event_get_state_backends(TRACE_VHOST_VDPA_GET_CONFIG) && trace_event_get_state_backends(TRACE_VHOST_VDPA_DUMP_CONFIG)) { vhost_vdpa_dump_config(dev, config, config_len); diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h index d563630cc9..60374785fd 100644 --- a/include/hw/virtio/vhost-vdpa.h +++ b/include/hw/virtio/vhost-vdpa.h @@ -41,6 +41,8 @@ typedef struct vhost_vdpa { uint64_t acked_features; uint64_t features; uint8_t status; + struct vhost_vdpa_config *config; + bool config_cache_enabled; bool shadow_vqs_enabled; /* Vdpa must send shadow addresses as IOTLB key for data queues, not G= PA */ bool shadow_data; --=20 2.25.1