[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v2 1/3] accel/tcg: split CpusAccel into three TCG variants
|
From: |
Philippe Mathieu-Daudé |
|
Subject: |
Re: [PATCH v2 1/3] accel/tcg: split CpusAccel into three TCG variants |
|
Date: |
Wed, 14 Oct 2020 21:37:02 +0200 |
|
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.1 |
On 10/14/20 9:23 PM, Claudio Fontana wrote:
split up the CpusAccel tcg_cpus into three TCG variants:
tcg_cpus_rr (single threaded, round robin cpus)
tcg_cpus_icount (same as rr, but with instruction counting enabled)
tcg_cpus_mttcg (multi-threaded cpus)
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Claudio Fontana <cfontana@suse.de>
---
accel/tcg/meson.build | 9 +-
accel/tcg/tcg-all.c | 8 +-
accel/tcg/tcg-cpus-icount.c | 147 +++++++++++
accel/tcg/tcg-cpus-icount.h | 17 ++
accel/tcg/tcg-cpus-mttcg.c | 119 +++++++++
accel/tcg/tcg-cpus-mttcg.h | 23 ++
accel/tcg/tcg-cpus-rr.c | 272 ++++++++++++++++++++
accel/tcg/tcg-cpus-rr.h | 21 ++
accel/tcg/tcg-cpus.c | 484 ++----------------------------------
accel/tcg/tcg-cpus.h | 13 +-
softmmu/icount.c | 2 +-
11 files changed, 653 insertions(+), 462 deletions(-)
...
diff --git a/accel/tcg/tcg-cpus-mttcg.c b/accel/tcg/tcg-cpus-mttcg.c
new file mode 100644
index 0000000000..723703fa3e
--- /dev/null
+++ b/accel/tcg/tcg-cpus-mttcg.c
@@ -0,0 +1,119 @@
+/*
+ * QEMU TCG Multi Threaded vCPUs implementation
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2014 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "sysemu/tcg.h"
+#include "sysemu/replay.h"
+#include "qemu/main-loop.h"
+#include "qemu/guest-random.h"
+#include "exec/exec-all.h"
+#include "hw/boards.h"
+
+#include "tcg-cpus.h"
+#include "tcg-cpus-mttcg.h"
+
+/*
+ * Multi-threaded TCG
Can drop this comment ^ and keep v.
+ *
+ * In the multi-threaded case each vCPU has its own thread. The TLS
+ * variable current_cpu can be used deep in the code to find the
+ * current CPUState for a given thread.
+ */
+
+void *tcg_cpu_thread_fn(void *arg)
+{
+ CPUState *cpu = arg;
+
+ assert(tcg_enabled());
+ g_assert(!icount_enabled());
+
+ rcu_register_thread();
+ tcg_register_thread();
+
+ qemu_mutex_lock_iothread();
+ qemu_thread_get_self(cpu->thread);
+
+ cpu->thread_id = qemu_get_thread_id();
+ cpu->can_do_io = 1;
+ current_cpu = cpu;
+ cpu_thread_signal_created(cpu);
+ qemu_guest_random_seed_thread_part2(cpu->random_seed);
+
+ /* process any pending work */
+ cpu->exit_request = 1;
+
+ do {
+ if (cpu_can_run(cpu)) {
+ int r;
+ qemu_mutex_unlock_iothread();
+ r = tcg_cpu_exec(cpu);
+ qemu_mutex_lock_iothread();
+ switch (r) {
+ case EXCP_DEBUG:
+ cpu_handle_guest_debug(cpu);
+ break;
+ case EXCP_HALTED:
+ /*
+ * during start-up the vCPU is reset and the thread is
+ * kicked several times. If we don't ensure we go back
+ * to sleep in the halted state we won't cleanly
+ * start-up when the vCPU is enabled.
+ *
+ * cpu->halted should ensure we sleep in wait_io_event
+ */
+ 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;
+ }
+ }
+
+ qatomic_mb_set(&cpu->exit_request, 0);
+ qemu_wait_io_event(cpu);
+ } while (!cpu->unplug || cpu_can_run(cpu));
+
+ qemu_tcg_destroy_vcpu(cpu);
+ qemu_mutex_unlock_iothread();
+ rcu_unregister_thread();
+ return NULL;
+}
...
diff --git a/accel/tcg/tcg-cpus-mttcg.h b/accel/tcg/tcg-cpus-mttcg.h
new file mode 100644
index 0000000000..5d203243e8
--- /dev/null
+++ b/accel/tcg/tcg-cpus-mttcg.h
@@ -0,0 +1,23 @@
+/*
+ * QEMU TCG Multi Threaded vCPUs implementation
+ *
+ * Copyright 2020 SUSE LLC
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef TCG_CPUS_MTTCG_H
+#define TCG_CPUS_MTTCG_H
+
+/*
+ * Multi-threaded TCG
Drop too ^
+ *
+ * In the multi-threaded case each vCPU has its own thread. The TLS
+ * variable current_cpu can be used deep in the code to find the
+ * current CPUState for a given thread.
+ */
+
+void *tcg_cpu_thread_fn(void *arg);
+
+#endif /* TCG_CPUS_MTTCG_H */
diff --git a/accel/tcg/tcg-cpus-rr.c b/accel/tcg/tcg-cpus-rr.c
new file mode 100644
index 0000000000..82bb7c5ea6
--- /dev/null
+++ b/accel/tcg/tcg-cpus-rr.c
@@ -0,0 +1,272 @@
+/*
+ * QEMU TCG Single Threaded vCPUs implementation
+ *
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2014 Red Hat Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "sysemu/tcg.h"
+#include "sysemu/replay.h"
+#include "qemu/main-loop.h"
+#include "qemu/guest-random.h"
+#include "exec/exec-all.h"
+#include "hw/boards.h"
+
+#include "tcg-cpus.h"
+#include "tcg-cpus-rr.h"
+#include "tcg-cpus-icount.h"
+
+/* Kick all RR vCPUs */
+void qemu_cpu_kick_rr_cpus(CPUState *unused)
+{
+ CPUState *cpu;
+
+ CPU_FOREACH(cpu) {
+ cpu_exit(cpu);
+ };
+}
+
+/*
+ * TCG vCPU kick timer
+ *
+ * The kick timer is responsible for moving single threaded vCPU
+ * emulation on to the next vCPU. If more than one vCPU is running a
+ * timer event with force a cpu->exit so the next vCPU can get
+ * scheduled.
+ *
+ * The timer is removed if all vCPUs are idle and restarted again once
+ * idleness is complete.
+ */
+
+static QEMUTimer *tcg_kick_vcpu_timer;
+static CPUState *tcg_current_rr_cpu;
+
+#define TCG_KICK_PERIOD (NANOSECONDS_PER_SECOND / 10)
+
+static inline int64_t qemu_tcg_next_kick(void)
+{
+ return qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + TCG_KICK_PERIOD;
+}
+
+/* Kick the currently round-robin scheduled vCPU to next */
+static void qemu_cpu_kick_rr_next_cpu(void)
+{
+ CPUState *cpu;
+ do {
+ cpu = qatomic_mb_read(&tcg_current_rr_cpu);
+ if (cpu) {
+ cpu_exit(cpu);
+ }
+ } while (cpu != qatomic_mb_read(&tcg_current_rr_cpu));
+}
+
+static void kick_tcg_thread(void *opaque)
+{
+ timer_mod(tcg_kick_vcpu_timer, qemu_tcg_next_kick());
+ qemu_cpu_kick_rr_next_cpu();
+}
+
+static void start_tcg_kick_timer(void)
+{
+ if (!tcg_kick_vcpu_timer && CPU_NEXT(first_cpu)) {
+ tcg_kick_vcpu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
+ kick_tcg_thread, NULL);
+ }
+ if (tcg_kick_vcpu_timer && !timer_pending(tcg_kick_vcpu_timer)) {
+ timer_mod(tcg_kick_vcpu_timer, qemu_tcg_next_kick());
+ }
+}
+
+static void stop_tcg_kick_timer(void)
+{
+ if (tcg_kick_vcpu_timer && timer_pending(tcg_kick_vcpu_timer)) {
+ timer_del(tcg_kick_vcpu_timer);
+ }
+}
+
+static void qemu_tcg_rr_wait_io_event(void)
+{
+ CPUState *cpu;
+
+ while (all_cpu_threads_idle()) {
+ stop_tcg_kick_timer();
+ qemu_cond_wait_iothread(first_cpu->halt_cond);
+ }
+
+ start_tcg_kick_timer();
+
+ CPU_FOREACH(cpu) {
+ qemu_wait_io_event_common(cpu);
+ }
+}
+
+/*
+ * Destroy any remaining vCPUs which have been unplugged and have
+ * finished running
+ */
+static void deal_with_unplugged_cpus(void)
+{
+ CPUState *cpu;
+
+ CPU_FOREACH(cpu) {
+ if (cpu->unplug && !cpu_can_run(cpu)) {
+ qemu_tcg_destroy_vcpu(cpu);
+ break;
+ }
+ }
+}
+
+/*
+ * Single-threaded TCG
Drop ^
+ *
+ * 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.
+ */
...
diff --git a/accel/tcg/tcg-cpus-rr.h b/accel/tcg/tcg-cpus-rr.h
new file mode 100644
index 0000000000..12463b0b93
--- /dev/null
+++ b/accel/tcg/tcg-cpus-rr.h
@@ -0,0 +1,21 @@
+/*
+ * QEMU TCG Single Threaded vCPUs implementation
+ *
+ * Copyright 2020 SUSE LLC
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef TCG_CPUS_RR_H
+#define TCG_CPUS_RR_H
+
+#define TCG_KICK_PERIOD (NANOSECONDS_PER_SECOND / 10)
+
+/* Kick all RR vCPUs. */
+void qemu_cpu_kick_rr_cpus(CPUState *unused);
+
+/* Single-threaded TCG */
Comment not helpful.
+void *tcg_rr_cpu_thread_fn(void *arg);
+
+#endif /* TCG_CPUS_RR_H */
diff --git a/accel/tcg/tcg-cpus.c b/accel/tcg/tcg-cpus.c
index da1c63d8f6..60d307dba1 100644
--- a/accel/tcg/tcg-cpus.c
+++ b/accel/tcg/tcg-cpus.c
@@ -1,5 +1,7 @@
/*
- * QEMU System Emulator
+ * QEMU TCG vcpu common functionality
"vCPU" as used elsewhere.
+ *
+ * Functionality common to all TCG vcpu variants: mttcg, rr and icount.
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2014 Red Hat Inc.
@@ -33,436 +35,12 @@
#include "hw/boards.h"
#include "tcg-cpus.h"
+#include "tcg-cpus-mttcg.h"
+#include "tcg-cpus-rr.h"
diff --git a/accel/tcg/tcg-cpus.h b/accel/tcg/tcg-cpus.h
index 8b1d9d2abc..cb61aed1cc 100644
--- a/accel/tcg/tcg-cpus.h
+++ b/accel/tcg/tcg-cpus.h
@@ -1,5 +1,7 @@
/*
- * Accelerator CPUS Interface
+ * QEMU TCG vcpu common functionality
"vCPU"
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>