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Tsirkin" , Eduardo Habkost , Marcel Apfelbaum , Kevin Wolf , Eric Blake , qemu-block@nongnu.org, Peter Xu , "Richard W.M. Jones" , Laurent Vivier , Richard Henderson , David Hildenbrand , Yanan Wang , Vladimir Sementsov-Ogievskiy , Markus Armbruster , Hanna Reitz , Fam Zheng , Xie Changlong , Jeff Cody , John Snow , "Denis V. Lunev" Subject: [PULL 01/13] coroutine: add flag to re-queue at front of CoQueue Date: Wed, 26 Oct 2022 14:58:34 -0400 Message-Id: <20221026185846.120544-2-stefanha@redhat.com> In-Reply-To: <20221026185846.120544-1-stefanha@redhat.com> References: <20221026185846.120544-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 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=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.515, 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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1666811232377100003 Content-Type: text/plain; charset="utf-8" When a coroutine wakes up it may determine that it must re-queue. Normally coroutines are pushed onto the back of the CoQueue, but for fairness it may be necessary to push it onto the front of the CoQueue. Add a flag to specify that the coroutine should be pushed onto the front of the CoQueue. A later patch will use this to ensure fairness in the bounce buffer CoQueue used by the blkio BlockDriver. Signed-off-by: Stefan Hajnoczi Message-id: 20221013185908.1297568-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- include/qemu/coroutine.h | 15 +++++++++++++-- util/qemu-coroutine-lock.c | 9 +++++++-- 2 files changed, 20 insertions(+), 4 deletions(-) diff --git a/include/qemu/coroutine.h b/include/qemu/coroutine.h index aae33cce17..608fe45dcf 100644 --- a/include/qemu/coroutine.h +++ b/include/qemu/coroutine.h @@ -198,14 +198,25 @@ typedef struct CoQueue { */ void qemu_co_queue_init(CoQueue *queue); =20 +typedef enum { + /* + * Enqueue at front instead of back. Use this to re-queue a request wh= en + * its wait condition is not satisfied after being woken up. + */ + CO_QUEUE_WAIT_FRONT =3D 0x1, +} CoQueueWaitFlags; + /** * Adds the current coroutine to the CoQueue and transfers control to the * caller of the coroutine. The mutex is unlocked during the wait and * locked again afterwards. */ #define qemu_co_queue_wait(queue, lock) \ - qemu_co_queue_wait_impl(queue, QEMU_MAKE_LOCKABLE(lock)) -void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lo= ck); + qemu_co_queue_wait_impl(queue, QEMU_MAKE_LOCKABLE(lock), 0) +#define qemu_co_queue_wait_flags(queue, lock, flags) \ + qemu_co_queue_wait_impl(queue, QEMU_MAKE_LOCKABLE(lock), (flags)) +void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lo= ck, + CoQueueWaitFlags flags); =20 /** * Removes the next coroutine from the CoQueue, and queue it to run after diff --git a/util/qemu-coroutine-lock.c b/util/qemu-coroutine-lock.c index 15c82d9348..45c6b57374 100644 --- a/util/qemu-coroutine-lock.c +++ b/util/qemu-coroutine-lock.c @@ -39,10 +39,15 @@ void qemu_co_queue_init(CoQueue *queue) QSIMPLEQ_INIT(&queue->entries); } =20 -void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lo= ck) +void coroutine_fn qemu_co_queue_wait_impl(CoQueue *queue, QemuLockable *lo= ck, + CoQueueWaitFlags flags) { Coroutine *self =3D qemu_coroutine_self(); - QSIMPLEQ_INSERT_TAIL(&queue->entries, self, co_queue_next); + if (flags & CO_QUEUE_WAIT_FRONT) { + QSIMPLEQ_INSERT_HEAD(&queue->entries, self, co_queue_next); + } else { + QSIMPLEQ_INSERT_TAIL(&queue->entries, self, co_queue_next); + } =20 if (lock) { qemu_lockable_unlock(lock); --=20 2.37.3