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Tue, 5 Apr 2016 16:32:33 +0100 (BST) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: mttcg@listserver.greensocs.com, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, serge.fdrv@gmail.com, cota@braap.org Date: Tue, 5 Apr 2016 16:32:22 +0100 Message-Id: <1459870344-16773-10-git-send-email-alex.bennee@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1459870344-16773-1-git-send-email-alex.bennee@linaro.org> References: <1459870344-16773-1-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a00:1450:400c:c09::233 Cc: peter.maydell@linaro.org, claudio.fontana@huawei.com, Peter Crosthwaite , jan.kiszka@siemens.com, mark.burton@greensocs.com, qemu-devel@nongnu.org, pbonzini@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , rth@twiddle.net Subject: [Qemu-devel] [RFC v2 09/11] tcg: add kick timer for single-threaded vCPU emulation X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently we rely on the side effect of the main loop grabbing the iothread_mutex to give any long running basic block chains a kick to ensure the next vCPU is scheduled. As this code is being re-factored and rationalised we now do it explicitly here. Signed-off-by: Alex Bennée --- v2 - re-base fixes - get_ticks_per_sec() -> NANOSECONDS_PER_SEC --- cpus.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/cpus.c b/cpus.c index 8d27fb0..e22bb77 100644 --- a/cpus.c +++ b/cpus.c @@ -1151,11 +1151,30 @@ static void *qemu_dummy_cpu_thread_fn(void *arg) #endif } +/* Single-threaded TCG + * + * In the single-threaded case each vCPU is simulated in turn. If + * there is more than a single vCPU we create a simple timer to kick + * the vCPU and ensure we don't get stuck in a tight loop in one vCPU. + * This is done explicitly rather than relying on side-effects + * elsewhere. + */ static int tcg_cpu_exec(CPUState *cpu); +static void qemu_cpu_kick_no_halt(void); + +static void kick_tcg_thread(void *opaque) +{ + QEMUTimer *self = *(QEMUTimer **) opaque; + timer_mod(self, + qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + + NANOSECONDS_PER_SECOND / 10); + qemu_cpu_kick_no_halt(); +} static void *qemu_tcg_cpu_thread_fn(void *arg) { CPUState *cpu = arg; + QEMUTimer *kick_timer; rcu_register_thread(); @@ -1179,6 +1198,14 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) } } + /* Set to kick if we have to do more than one vCPU */ + if (CPU_NEXT(first_cpu)) { + kick_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, kick_tcg_thread, &kick_timer); + timer_mod(kick_timer, + qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + + NANOSECONDS_PER_SECOND / 10); + } + /* process any pending work */ atomic_mb_set(&exit_request, 1);