From nobody Wed May 8 10:06:14 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1509447373092473.9584400420973; Tue, 31 Oct 2017 03:56:13 -0700 (PDT) Received: from localhost ([::1]:44725 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e9UDB-0003ge-Sy for importer@patchew.org; Tue, 31 Oct 2017 06:56:01 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57977) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e9U6B-00065c-Os for qemu-devel@nongnu.org; Tue, 31 Oct 2017 06:48:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e9U6A-0004kx-De for qemu-devel@nongnu.org; Tue, 31 Oct 2017 06:48:47 -0400 Received: from mail.ispras.ru ([83.149.199.45]:39948) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e9U6A-0004jV-1e for qemu-devel@nongnu.org; Tue, 31 Oct 2017 06:48:46 -0400 Received: from [127.0.1.1] (unknown [85.142.117.226]) by mail.ispras.ru (Postfix) with ESMTPSA id 51E5254006A; Tue, 31 Oct 2017 13:48:45 +0300 (MSK) From: Pavel Dovgalyuk To: qemu-devel@nongnu.org Date: Tue, 31 Oct 2017 13:48:46 +0300 Message-ID: <20171031104846.3079.43409.stgit@pasha-VirtualBox> In-Reply-To: <20171031104741.3079.26584.stgit@pasha-VirtualBox> References: <20171031104741.3079.26584.stgit@pasha-VirtualBox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 83.149.199.45 Subject: [Qemu-devel] [RFCPATCH12/20] cpus: push BQL lock to qemu_*_wait_io_event X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: dovgaluk@ispras.ru Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 From: Alex Benn=C3=A9e We only really need to grab the lock for initial setup (so we don't race with the thread-spawning thread). After that we can drop the lock for the whole main loop and only grab it for waiting for IO events. There is a slight wrinkle for the round-robin TCG thread as we also expire timers which needs to be done under BQL as they are in the main-loop. This is stage one of reducing the lock impact as we can drop the requirement of implicit BQL for async work and only grab the lock when we need to sleep on the cpu->halt_cond. Signed-off-by: Alex Benn=C3=A9e Signed-off-by: Pavel Dovgalyuk --- accel/kvm/kvm-all.c | 4 ---- cpus.c | 27 ++++++++++++++++++++------- target/i386/hax-all.c | 3 +-- 3 files changed, 21 insertions(+), 13 deletions(-) diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index f290f48..8d1d2c4 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -1857,9 +1857,7 @@ int kvm_cpu_exec(CPUState *cpu) return EXCP_HLT; } =20 - qemu_mutex_unlock_iothread(); cpu_exec_start(cpu); - do { MemTxAttrs attrs; =20 @@ -1989,8 +1987,6 @@ int kvm_cpu_exec(CPUState *cpu) } while (ret =3D=3D 0); =20 cpu_exec_end(cpu); - qemu_mutex_lock_iothread(); - if (ret < 0) { cpu_dump_state(cpu, stderr, fprintf, CPU_DUMP_CODE); vm_stop(RUN_STATE_INTERNAL_ERROR); diff --git a/cpus.c b/cpus.c index 2eec54f..efde5c1 100644 --- a/cpus.c +++ b/cpus.c @@ -1127,6 +1127,8 @@ static bool qemu_tcg_should_sleep(CPUState *cpu) =20 static void qemu_tcg_wait_io_event(CPUState *cpu) { + qemu_mutex_lock_iothread(); + while (qemu_tcg_should_sleep(cpu)) { stop_tcg_kick_timer(); qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex); @@ -1135,15 +1137,21 @@ static void qemu_tcg_wait_io_event(CPUState *cpu) start_tcg_kick_timer(); =20 qemu_wait_io_event_common(cpu); + + qemu_mutex_unlock_iothread(); } =20 static void qemu_kvm_wait_io_event(CPUState *cpu) { + qemu_mutex_lock_iothread(); + while (cpu_thread_is_idle(cpu)) { qemu_cond_wait(cpu->halt_cond, &qemu_global_mutex); } =20 qemu_wait_io_event_common(cpu); + + qemu_mutex_unlock_iothread(); } =20 static void *qemu_kvm_cpu_thread_fn(void *arg) @@ -1169,6 +1177,8 @@ static void *qemu_kvm_cpu_thread_fn(void *arg) =20 /* signal CPU creation */ cpu->created =3D true; + qemu_mutex_unlock_iothread(); + qemu_cond_signal(&qemu_cpu_cond); =20 do { @@ -1211,10 +1221,10 @@ static void *qemu_dummy_cpu_thread_fn(void *arg) =20 /* signal CPU creation */ cpu->created =3D true; + qemu_mutex_unlock_iothread(); qemu_cond_signal(&qemu_cpu_cond); =20 while (1) { - qemu_mutex_unlock_iothread(); do { int sig; r =3D sigwait(&waitset, &sig); @@ -1225,6 +1235,7 @@ static void *qemu_dummy_cpu_thread_fn(void *arg) } qemu_mutex_lock_iothread(); qemu_wait_io_event_common(cpu); + qemu_mutex_unlock_iothread(); } =20 return NULL; @@ -1313,11 +1324,9 @@ static int tcg_cpu_exec(CPUState *cpu) #ifdef CONFIG_PROFILER ti =3D profile_getclock(); #endif - qemu_mutex_unlock_iothread(); cpu_exec_start(cpu); ret =3D cpu_exec(cpu); cpu_exec_end(cpu); - qemu_mutex_lock_iothread(); #ifdef CONFIG_PROFILER tcg_time +=3D profile_getclock() - ti; #endif @@ -1377,6 +1386,7 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg) qemu_wait_io_event_common(cpu); } } + qemu_mutex_unlock_iothread(); =20 start_tcg_kick_timer(); =20 @@ -1386,6 +1396,9 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg) cpu->exit_request =3D 1; =20 while (1) { + + qemu_mutex_lock_iothread(); + /* Account partial waits to QEMU_CLOCK_VIRTUAL. */ qemu_account_warp_timer(); =20 @@ -1394,6 +1407,8 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg) */ handle_icount_deadline(); =20 + qemu_mutex_unlock_iothread(); + if (!cpu) { cpu =3D first_cpu; } @@ -1419,9 +1434,7 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg) cpu_handle_guest_debug(cpu); break; } else if (r =3D=3D EXCP_ATOMIC) { - qemu_mutex_unlock_iothread(); cpu_exec_step_atomic(cpu); - qemu_mutex_lock_iothread(); break; } } else if (cpu->stop) { @@ -1462,6 +1475,7 @@ static void *qemu_hax_cpu_thread_fn(void *arg) current_cpu =3D cpu; =20 hax_init_vcpu(cpu); + qemu_mutex_unlock_iothread(); qemu_cond_signal(&qemu_cpu_cond); =20 while (1) { @@ -1512,6 +1526,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) cpu->created =3D true; cpu->can_do_io =3D 1; current_cpu =3D cpu; + qemu_mutex_unlock_iothread(); qemu_cond_signal(&qemu_cpu_cond); =20 /* process any pending work */ @@ -1536,9 +1551,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) g_assert(cpu->halted); break; case EXCP_ATOMIC: - qemu_mutex_unlock_iothread(); cpu_exec_step_atomic(cpu); - qemu_mutex_lock_iothread(); default: /* Ignore everything else? */ break; diff --git a/target/i386/hax-all.c b/target/i386/hax-all.c index 3ce6950..99af6bb 100644 --- a/target/i386/hax-all.c +++ b/target/i386/hax-all.c @@ -513,11 +513,10 @@ static int hax_vcpu_hax_exec(CPUArchState *env) =20 hax_vcpu_interrupt(env); =20 - qemu_mutex_unlock_iothread(); cpu_exec_start(cpu); hax_ret =3D hax_vcpu_run(vcpu); + current_cpu =3D cpu; cpu_exec_end(cpu); - qemu_mutex_lock_iothread(); =20 /* Simply continue the vcpu_run if system call interrupted */ if (hax_ret =3D=3D -EINTR || hax_ret =3D=3D -EAGAIN) {