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Sat, 10 Oct 2020 20:41:59 +0000 (UTC) Received: from localhost (unknown [10.36.110.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 280115C1D7; Sat, 10 Oct 2020 20:41:48 +0000 (UTC) From: marcandre.lureau@redhat.com To: qemu-devel@nongnu.org Subject: [PATCH 3/3] console: make QMP/HMP screendump run in coroutine Date: Sun, 11 Oct 2020 00:41:06 +0400 Message-Id: <20201010204106.1368710-4-marcandre.lureau@redhat.com> In-Reply-To: <20201010204106.1368710-1-marcandre.lureau@redhat.com> References: <20201010204106.1368710-1-marcandre.lureau@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=marcandre.lureau@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=63.128.21.124; envelope-from=marcandre.lureau@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/10 16:30:21 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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, DKIMWL_WL_HIGH=-0.001, 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 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Markus Armbruster , "Dr. David Alan Gilbert" , Gerd Hoffmann , Stefan Hajnoczi , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Marc-André Lureau Thanks to the monitors coroutine support, the screendump handler can trigger a graphic_hw_update(), yield and let the main loop run until update is done. Then the handler is resumed, and ppm_save() will write the screen image to disk in the coroutine context (thus non-blocking). Potentially, during non-blocking write, some new graphic update could happen, and thus the image may have some glitches. Whether that behaviour is acceptable is discutable. Allocating new memory may not be a good idea, as framebuffers can be quite large. Even then, QEMU may become less responsive as it requires paging in etc. Related to: https://bugzilla.redhat.com/show_bug.cgi?id=1230527 Signed-off-by: Marc-André Lureau --- hmp-commands.hx | 1 + monitor/hmp-cmds.c | 3 ++- qapi/ui.json | 3 ++- ui/console.c | 27 ++++++++++++++++++++++++--- 4 files changed, 29 insertions(+), 5 deletions(-) diff --git a/hmp-commands.hx b/hmp-commands.hx index cd068389de..ff2d7aa8f3 100644 --- a/hmp-commands.hx +++ b/hmp-commands.hx @@ -254,6 +254,7 @@ ERST .help = "save screen from head 'head' of display device 'device' " "into PPM image 'filename'", .cmd = hmp_screendump, + .coroutine = true, }, SRST diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c index 9789f4277f..91608bac6d 100644 --- a/monitor/hmp-cmds.c +++ b/monitor/hmp-cmds.c @@ -1756,7 +1756,8 @@ err_out: goto out; } -void hmp_screendump(Monitor *mon, const QDict *qdict) +void coroutine_fn +hmp_screendump(Monitor *mon, const QDict *qdict) { const char *filename = qdict_get_str(qdict, "filename"); const char *id = qdict_get_try_str(qdict, "device"); diff --git a/qapi/ui.json b/qapi/ui.json index 9d6721037f..6c7b33cb72 100644 --- a/qapi/ui.json +++ b/qapi/ui.json @@ -98,7 +98,8 @@ # ## { 'command': 'screendump', - 'data': {'filename': 'str', '*device': 'str', '*head': 'int'} } + 'data': {'filename': 'str', '*device': 'str', '*head': 'int'}, + 'coroutine': true } ## # == Spice diff --git a/ui/console.c b/ui/console.c index a56fe0dd26..0118f70d9a 100644 --- a/ui/console.c +++ b/ui/console.c @@ -168,6 +168,7 @@ struct QemuConsole { QEMUFIFO out_fifo; uint8_t out_fifo_buf[16]; QEMUTimer *kbd_timer; + CoQueue dump_queue; QTAILQ_ENTRY(QemuConsole) next; }; @@ -263,6 +264,7 @@ static void gui_setup_refresh(DisplayState *ds) void graphic_hw_update_done(QemuConsole *con) { + qemu_co_queue_restart_all(&con->dump_queue); } void graphic_hw_update(QemuConsole *con) @@ -340,8 +342,15 @@ static bool ppm_save(int fd, pixman_image_t *image, Error **errp) return true; } -void qmp_screendump(const char *filename, bool has_device, const char *device, - bool has_head, int64_t head, Error **errp) +static void graphic_hw_update_bh(void *con) +{ + graphic_hw_update(con); +} + +/* Safety: coroutine-only, concurrent-coroutine safe, main thread only */ +void coroutine_fn +qmp_screendump(const char *filename, bool has_device, const char *device, + bool has_head, int64_t head, Error **errp) { g_autoptr(pixman_image_t) image = NULL; QemuConsole *con; @@ -366,7 +375,15 @@ void qmp_screendump(const char *filename, bool has_device, const char *device, } } - graphic_hw_update(con); + if (qemu_co_queue_empty(&con->dump_queue)) { + /* Defer the update, it will restart the pending coroutines */ + aio_bh_schedule_oneshot(qemu_get_aio_context(), + graphic_hw_update_bh, con); + } + qemu_co_queue_wait(&con->dump_queue, NULL); + + /* All pending coroutines are woken up, while BQL taken, no further graphic + * update are possible until it is released, take an image ref before that. */ surface = qemu_console_surface(con); if (!surface) { error_setg(errp, "no surface"); @@ -381,6 +398,9 @@ void qmp_screendump(const char *filename, bool has_device, const char *device, return; } + /* The image content could potentially be updated as the coroutine yields + * and releases the BQL. It could produce corrupted dump, but it should be + * otherwise safe. */ if (!ppm_save(fd, image, errp)) { qemu_unlink(filename); } @@ -1297,6 +1317,7 @@ static QemuConsole *new_console(DisplayState *ds, console_type_t console_type, obj = object_new(TYPE_QEMU_CONSOLE); s = QEMU_CONSOLE(obj); + qemu_co_queue_init(&s->dump_queue); s->head = head; object_property_add_link(obj, "device", TYPE_DEVICE, (Object **)&s->device,