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cpu-timers, icount: new modules

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refactoring of cpus.c continues with cpu timer state extraction.

cpu-timers: responsible for the softmmu cpu timers state,
            including cpu clocks and ticks.

icount: counts the TCG instructions executed. As such it is specific to
the TCG accelerator. Therefore, it is built only under CONFIG_TCG.

One complication is due to qtest, which uses an icount field to warp time
as part of qtest (qtest_clock_warp).

In order to solve this problem, provide a separate counter for qtest.

This requires fixing assumptions scattered in the code that
qtest_enabled() implies icount_enabled(), checking each specific case.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
[remove redundant initialization with qemu_spice_init]
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
[fix lingering calls to icount_get]
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Claudio Fontana
2020-10-05 16:41:22 +02:00
committed by Paolo Bonzini
parent 0ac0b47c44
commit 740b175973
37 changed files with 1128 additions and 843 deletions
Download Patch File Download Diff File Expand all files Collapse all files
MAINTAINERS
+2
View File
@@ -2321,6 +2321,8 @@ F: softmmu/vl.c
F: softmmu/main.c
F: softmmu/cpus.c
F: softmmu/cpu-throttle.c
F: softmmu/cpu-timers.c
F: softmmu/icount.c
F: qapi/run-state.json
Read, Copy, Update (RCU)
accel/qtest.c
+1 -5
View File
@@ -19,14 +19,10 @@
#include "sysemu/accel.h"
#include "sysemu/qtest.h"
#include "sysemu/cpus.h"
#include "sysemu/cpu-timers.h"
static int qtest_init_accel(MachineState *ms)
{
QemuOpts *opts = qemu_opts_create(qemu_find_opts("icount"), NULL, 0,
&error_abort);
qemu_opt_set(opts, "shift", "0", &error_abort);
configure_icount(opts, &error_abort);
qemu_opts_del(opts);
return 0;
}
accel/tcg/cpu-exec.c
+34 -5
View File
@@ -19,6 +19,7 @@
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "qemu/qemu-print.h"
#include "cpu.h"
#include "trace.h"
#include "disas/disas.h"
@@ -36,6 +37,8 @@
#include "hw/i386/apic.h"
#endif
#include "sysemu/cpus.h"
#include "exec/cpu-all.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/replay.h"
/* -icount align implementation. */
@@ -56,6 +59,9 @@ typedef struct SyncClocks {
#define MAX_DELAY_PRINT_RATE 2000000000LL
#define MAX_NB_PRINTS 100
static int64_t max_delay;
static int64_t max_advance;
static void align_clocks(SyncClocks *sc, CPUState *cpu)
{
int64_t cpu_icount;
@@ -98,9 +104,9 @@ static void print_delay(const SyncClocks *sc)
(-sc->diff_clk / (float)1000000000LL <
(threshold_delay - THRESHOLD_REDUCE))) {
threshold_delay = (-sc->diff_clk / 1000000000LL) + 1;
printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
threshold_delay - 1,
threshold_delay);
qemu_printf("Warning: The guest is now late by %.1f to %.1f seconds\n",
threshold_delay - 1,
threshold_delay);
nb_prints++;
last_realtime_clock = sc->realtime_clock;
}
@@ -615,7 +621,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
/* Finally, check if we need to exit to the main loop. */
if (unlikely(qatomic_read(&cpu->exit_request))
|| (use_icount
|| (icount_enabled()
&& cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra == 0)) {
qatomic_set(&cpu->exit_request, 0);
if (cpu->exception_index == -1) {
@@ -656,7 +662,7 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
}
/* Instruction counter expired. */
assert(use_icount);
assert(icount_enabled());
#ifndef CONFIG_USER_ONLY
/* Ensure global icount has gone forward */
cpu_update_icount(cpu);
@@ -759,3 +765,26 @@ int cpu_exec(CPUState *cpu)
return ret;
}
#ifndef CONFIG_USER_ONLY
void dump_drift_info(void)
{
if (!icount_enabled()) {
return;
}
qemu_printf("Host - Guest clock %"PRIi64" ms\n",
(cpu_get_clock() - cpu_get_icount()) / SCALE_MS);
if (icount_align_option) {
qemu_printf("Max guest delay %"PRIi64" ms\n",
-max_delay / SCALE_MS);
qemu_printf("Max guest advance %"PRIi64" ms\n",
max_advance / SCALE_MS);
} else {
qemu_printf("Max guest delay NA\n");
qemu_printf("Max guest advance NA\n");
}
}
#endif /* !CONFIG_USER_ONLY */
accel/tcg/tcg-all.c
+4 -3
View File
@@ -29,6 +29,7 @@
#include "qom/object.h"
#include "cpu.h"
#include "sysemu/cpus.h"
#include "sysemu/cpu-timers.h"
#include "qemu/main-loop.h"
#include "tcg/tcg.h"
#include "qapi/error.h"
@@ -66,7 +67,7 @@ static void tcg_handle_interrupt(CPUState *cpu, int mask)
qemu_cpu_kick(cpu);
} else {
qatomic_set(&cpu_neg(cpu)->icount_decr.u16.high, -1);
if (use_icount &&
if (icount_enabled() &&
!cpu->can_do_io
&& (mask & ~old_mask) != 0) {
cpu_abort(cpu, "Raised interrupt while not in I/O function");
@@ -105,7 +106,7 @@ static bool check_tcg_memory_orders_compatible(void)
static bool default_mttcg_enabled(void)
{
if (use_icount || TCG_OVERSIZED_GUEST) {
if (icount_enabled() || TCG_OVERSIZED_GUEST) {
return false;
} else {
#ifdef TARGET_SUPPORTS_MTTCG
@@ -147,7 +148,7 @@ static void tcg_set_thread(Object *obj, const char *value, Error **errp)
if (strcmp(value, "multi") == 0) {
if (TCG_OVERSIZED_GUEST) {
error_setg(errp, "No MTTCG when guest word size > hosts");
} else if (use_icount) {
} else if (icount_enabled()) {
error_setg(errp, "No MTTCG when icount is enabled");
} else {
#ifndef TARGET_SUPPORTS_MTTCG
accel/tcg/translate-all.c
+2 -1
View File
@@ -57,6 +57,7 @@
#include "qemu/main-loop.h"
#include "exec/log.h"
#include "sysemu/cpus.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/tcg.h"
/* #define DEBUG_TB_INVALIDATE */
@@ -369,7 +370,7 @@ static int cpu_restore_state_from_tb(CPUState *cpu, TranslationBlock *tb,
found:
if (reset_icount && (tb_cflags(tb) & CF_USE_ICOUNT)) {
assert(use_icount);
assert(icount_enabled());
/* Reset the cycle counter to the start of the block
and shift if to the number of actually executed instructions */
cpu_neg(cpu)->icount_decr.u16.low += num_insns - i;
dma-helpers.c
+2 -2
View File
@@ -13,7 +13,7 @@
#include "trace/trace-root.h"
#include "qemu/thread.h"
#include "qemu/main-loop.h"
#include "sysemu/cpus.h"
#include "sysemu/cpu-timers.h"
#include "qemu/range.h"
/* #define DEBUG_IOMMU */
@@ -151,7 +151,7 @@ static void dma_blk_cb(void *opaque, int ret)
* from several sectors. This code splits all SGs into several
* groups. SGs in every group do not overlap.
*/
if (mem && use_icount && dbs->dir == DMA_DIRECTION_FROM_DEVICE) {
if (mem && icount_enabled() && dbs->dir == DMA_DIRECTION_FROM_DEVICE) {
int i;
for (i = 0 ; i < dbs->iov.niov ; ++i) {
if (ranges_overlap((intptr_t)dbs->iov.iov[i].iov_base,
exec.c
-4
View File
@@ -102,10 +102,6 @@ uintptr_t qemu_host_page_size;
intptr_t qemu_host_page_mask;
#if !defined(CONFIG_USER_ONLY)
/* 0 = Do not count executed instructions.
1 = Precise instruction counting.
2 = Adaptive rate instruction counting. */
int use_icount;
typedef struct PhysPageEntry PhysPageEntry;
hw/core/ptimer.c
+5 -3
View File
@@ -7,11 +7,11 @@
*/
#include "qemu/osdep.h"
#include "qemu/timer.h"
#include "hw/ptimer.h"
#include "migration/vmstate.h"
#include "qemu/host-utils.h"
#include "sysemu/replay.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/qtest.h"
#include "block/aio.h"
#include "sysemu/cpus.h"
@@ -134,7 +134,8 @@ static void ptimer_reload(ptimer_state *s, int delta_adjust)
* on the current generation of host machines.
*/
if (s->enabled == 1 && (delta * period < 10000) && !use_icount) {
if (s->enabled == 1 && (delta * period < 10000) &&
!icount_enabled() && !qtest_enabled()) {
period = 10000 / delta;
period_frac = 0;
}
@@ -217,7 +218,8 @@ uint64_t ptimer_get_count(ptimer_state *s)
uint32_t period_frac = s->period_frac;
uint64_t period = s->period;
if (!oneshot && (s->delta * period < 10000) && !use_icount) {
if (!oneshot && (s->delta * period < 10000) &&
!icount_enabled() && !qtest_enabled()) {
period = 10000 / s->delta;
period_frac = 0;
}
hw/i386/x86.c
+1
View File
@@ -34,6 +34,7 @@
#include "sysemu/numa.h"
#include "sysemu/replay.h"
#include "sysemu/sysemu.h"
#include "sysemu/cpu-timers.h"
#include "trace.h"
#include "hw/i386/x86.h"
include/exec/cpu-all.h
+4
View File
@@ -407,8 +407,12 @@ static inline bool tlb_hit(target_ulong tlb_addr, target_ulong addr)
return tlb_hit_page(tlb_addr, addr & TARGET_PAGE_MASK);
}
#ifdef CONFIG_TCG
void dump_drift_info(void);
void dump_exec_info(void);
void dump_opcount_info(void);
#endif /* CONFIG_TCG */
#endif /* !CONFIG_USER_ONLY */
/* Returns: 0 on success, -1 on error */
include/exec/exec-all.h
+2 -2
View File
@@ -25,7 +25,7 @@
#ifdef CONFIG_TCG
#include "exec/cpu_ldst.h"
#endif
#include "sysemu/cpus.h"
#include "sysemu/cpu-timers.h"
/* allow to see translation results - the slowdown should be negligible, so we leave it */
#define DEBUG_DISAS
@@ -497,7 +497,7 @@ static inline uint32_t tb_cflags(const TranslationBlock *tb)
static inline uint32_t curr_cflags(void)
{
return (parallel_cpus ? CF_PARALLEL : 0)
| (use_icount ? CF_USE_ICOUNT : 0);
| (icount_enabled() ? CF_USE_ICOUNT : 0);
}
/* TranslationBlock invalidate API */
include/qemu/timer.h
+2 -22
View File
@@ -166,8 +166,8 @@ bool qemu_clock_expired(QEMUClockType type);
*
* Determine whether a clock should be used for deadline
* calculations. Some clocks, for instance vm_clock with
* use_icount set, do not count in nanoseconds. Such clocks
* are not used for deadline calculations, and are presumed
* icount_enabled() set, do not count in nanoseconds.
* Such clocks are not used for deadline calculations, and are presumed
* to interrupt any poll using qemu_notify/aio_notify
* etc.
*
@@ -224,13 +224,6 @@ void qemu_clock_notify(QEMUClockType type);
*/
void qemu_clock_enable(QEMUClockType type, bool enabled);
/**
* qemu_start_warp_timer:
*
* Starts a timer for virtual clock update
*/
void qemu_start_warp_timer(void);
/**
* qemu_clock_run_timers:
* @type: clock on which to operate
@@ -791,12 +784,6 @@ static inline int64_t qemu_soonest_timeout(int64_t timeout1, int64_t timeout2)
*/
void init_clocks(QEMUTimerListNotifyCB *notify_cb);
int64_t cpu_get_ticks(void);
/* Caller must hold BQL */
void cpu_enable_ticks(void);
/* Caller must hold BQL */
void cpu_disable_ticks(void);
static inline int64_t get_max_clock_jump(void)
{
/* This should be small enough to prevent excessive interrupts from being
@@ -850,13 +837,6 @@ static inline int64_t get_clock(void)
}
#endif
/* icount */
int64_t cpu_get_icount_raw(void);
int64_t cpu_get_icount(void);
int64_t cpu_get_clock(void);
int64_t cpu_icount_to_ns(int64_t icount);
void cpu_update_icount(CPUState *cpu);
/*******************************************/
/* host CPU ticks (if available) */
include/sysemu/cpu-timers.h
+87
View File
@@ -0,0 +1,87 @@
/*
* CPU timers state API
*
* 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 SYSEMU_CPU_TIMERS_H
#define SYSEMU_CPU_TIMERS_H
#include "qemu/timer.h"
/* init the whole cpu timers API, including icount, ticks, and cpu_throttle */
void cpu_timers_init(void);
/* icount - Instruction Counter API */
/*
* icount enablement state:
*
* 0 = Disabled - Do not count executed instructions.
* 1 = Enabled - Fixed conversion of insn to ns via "shift" option
* 2 = Enabled - Runtime adaptive algorithm to compute shift
*/
#ifdef CONFIG_TCG
extern int use_icount;
#define icount_enabled() (use_icount)
#else
#define icount_enabled() 0
#endif
/*
* Update the icount with the executed instructions. Called by
* cpus-tcg vCPU thread so the main-loop can see time has moved forward.
*/
void cpu_update_icount(CPUState *cpu);
/* get raw icount value */
int64_t cpu_get_icount_raw(void);
/* return the virtual CPU time in ns, based on the instruction counter. */
int64_t cpu_get_icount(void);
/*
* convert an instruction counter value to ns, based on the icount shift.
* This shift is set as a fixed value with the icount "shift" option
* (precise mode), or it is constantly approximated and corrected at
* runtime in adaptive mode.
*/
int64_t cpu_icount_to_ns(int64_t icount);
/* configure the icount options, including "shift" */
void configure_icount(QemuOpts *opts, Error **errp);
/* used by tcg vcpu thread to calc icount budget */
int64_t qemu_icount_round(int64_t count);
/* if the CPUs are idle, start accounting real time to virtual clock. */
void qemu_start_warp_timer(void);
void qemu_account_warp_timer(void);
/*
* CPU Ticks and Clock
*/
/* Caller must hold BQL */
void cpu_enable_ticks(void);
/* Caller must hold BQL */
void cpu_disable_ticks(void);
/*
* return the time elapsed in VM between vm_start and vm_stop. Unless
* icount is active, cpu_get_ticks() uses units of the host CPU cycle
* counter.
*/
int64_t cpu_get_ticks(void);
/*
* Returns the monotonic time elapsed in VM, i.e.,
* the time between vm_start and vm_stop
*/
int64_t cpu_get_clock(void);
void qemu_timer_notify_cb(void *opaque, QEMUClockType type);
#endif /* SYSEMU_CPU_TIMERS_H */
include/sysemu/cpus.h
+1 -11
View File
@@ -4,33 +4,23 @@
#include "qemu/timer.h"
/* cpus.c */
bool all_cpu_threads_idle(void);
bool qemu_in_vcpu_thread(void);
void qemu_init_cpu_loop(void);
void resume_all_vcpus(void);
void pause_all_vcpus(void);
void cpu_stop_current(void);
void cpu_ticks_init(void);
void configure_icount(QemuOpts *opts, Error **errp);
extern int use_icount;
extern int icount_align_option;
/* drift information for info jit command */
extern int64_t max_delay;
extern int64_t max_advance;
void dump_drift_info(void);
/* Unblock cpu */
void qemu_cpu_kick_self(void);
void qemu_timer_notify_cb(void *opaque, QEMUClockType type);
void cpu_synchronize_all_states(void);
void cpu_synchronize_all_post_reset(void);
void cpu_synchronize_all_post_init(void);
void cpu_synchronize_all_pre_loadvm(void);
void qtest_clock_warp(int64_t dest);
#ifndef CONFIG_USER_ONLY
/* vl.c */
/* *-user doesn't have configurable SMP topology */
include/sysemu/qtest.h
+2
View File
@@ -30,4 +30,6 @@ void qtest_server_set_send_handler(void (*send)(void *, const char *),
void *opaque);
void qtest_server_inproc_recv(void *opaque, const char *buf);
int64_t qtest_get_virtual_clock(void);
#endif
replay/replay.c
+2 -2
View File
@@ -11,10 +11,10 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/replay.h"
#include "sysemu/runstate.h"
#include "replay-internal.h"
#include "qemu/timer.h"
#include "qemu/main-loop.h"
#include "qemu/option.h"
#include "sysemu/cpus.h"
@@ -345,7 +345,7 @@ void replay_start(void)
error_reportf_err(replay_blockers->data, "Record/replay: ");
exit(1);
}
if (!use_icount) {
if (!icount_enabled()) {
error_report("Please enable icount to use record/replay");
exit(1);
}
softmmu/cpu-timers.c
+284
View File
@@ -0,0 +1,284 @@
/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* 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 "qemu/cutils.h"
#include "migration/vmstate.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "exec/exec-all.h"
#include "sysemu/cpus.h"
#include "sysemu/qtest.h"
#include "qemu/main-loop.h"
#include "qemu/option.h"
#include "qemu/seqlock.h"
#include "sysemu/replay.h"
#include "sysemu/runstate.h"
#include "hw/core/cpu.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/cpu-throttle.h"
#include "timers-state.h"
/* clock and ticks */
static int64_t cpu_get_ticks_locked(void)
{
int64_t ticks = timers_state.cpu_ticks_offset;
if (timers_state.cpu_ticks_enabled) {
ticks += cpu_get_host_ticks();
}
if (timers_state.cpu_ticks_prev > ticks) {
/* Non increasing ticks may happen if the host uses software suspend. */
timers_state.cpu_ticks_offset += timers_state.cpu_ticks_prev - ticks;
ticks = timers_state.cpu_ticks_prev;
}
timers_state.cpu_ticks_prev = ticks;
return ticks;
}
/*
* return the time elapsed in VM between vm_start and vm_stop. Unless
* icount is active, cpu_get_ticks() uses units of the host CPU cycle
* counter.
*/
int64_t cpu_get_ticks(void)
{
int64_t ticks;
if (icount_enabled()) {
return cpu_get_icount();
}
qemu_spin_lock(&timers_state.vm_clock_lock);
ticks = cpu_get_ticks_locked();
qemu_spin_unlock(&timers_state.vm_clock_lock);
return ticks;
}
int64_t cpu_get_clock_locked(void)
{
int64_t time;
time = timers_state.cpu_clock_offset;
if (timers_state.cpu_ticks_enabled) {
time += get_clock();
}
return time;
}
/*
* Return the monotonic time elapsed in VM, i.e.,
* the time between vm_start and vm_stop
*/
int64_t cpu_get_clock(void)
{
int64_t ti;
unsigned start;
do {
start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
ti = cpu_get_clock_locked();
} while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
return ti;
}
/*
* enable cpu_get_ticks()
* Caller must hold BQL which serves as mutex for vm_clock_seqlock.
*/
void cpu_enable_ticks(void)
{
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (!timers_state.cpu_ticks_enabled) {
timers_state.cpu_ticks_offset -= cpu_get_host_ticks();
timers_state.cpu_clock_offset -= get_clock();
timers_state.cpu_ticks_enabled = 1;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
/*
* disable cpu_get_ticks() : the clock is stopped. You must not call
* cpu_get_ticks() after that.
* Caller must hold BQL which serves as mutex for vm_clock_seqlock.
*/
void cpu_disable_ticks(void)
{
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (timers_state.cpu_ticks_enabled) {
timers_state.cpu_ticks_offset += cpu_get_host_ticks();
timers_state.cpu_clock_offset = cpu_get_clock_locked();
timers_state.cpu_ticks_enabled = 0;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
static bool icount_state_needed(void *opaque)
{
return icount_enabled();
}
static bool warp_timer_state_needed(void *opaque)
{
TimersState *s = opaque;
return s->icount_warp_timer != NULL;
}
static bool adjust_timers_state_needed(void *opaque)
{
TimersState *s = opaque;
return s->icount_rt_timer != NULL;
}
static bool shift_state_needed(void *opaque)
{
return icount_enabled() == 2;
}
/*
* Subsection for warp timer migration is optional, because may not be created
*/
static const VMStateDescription icount_vmstate_warp_timer = {
.name = "timer/icount/warp_timer",
.version_id = 1,
.minimum_version_id = 1,
.needed = warp_timer_state_needed,
.fields = (VMStateField[]) {
VMSTATE_INT64(vm_clock_warp_start, TimersState),
VMSTATE_TIMER_PTR(icount_warp_timer, TimersState),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription icount_vmstate_adjust_timers = {
.name = "timer/icount/timers",
.version_id = 1,
.minimum_version_id = 1,
.needed = adjust_timers_state_needed,
.fields = (VMStateField[]) {
VMSTATE_TIMER_PTR(icount_rt_timer, TimersState),
VMSTATE_TIMER_PTR(icount_vm_timer, TimersState),
VMSTATE_END_OF_LIST()
}
};
static const VMStateDescription icount_vmstate_shift = {
.name = "timer/icount/shift",
.version_id = 1,
.minimum_version_id = 1,
.needed = shift_state_needed,
.fields = (VMStateField[]) {
VMSTATE_INT16(icount_time_shift, TimersState),
VMSTATE_END_OF_LIST()
}
};
/*
* This is a subsection for icount migration.
*/
static const VMStateDescription icount_vmstate_timers = {
.name = "timer/icount",
.version_id = 1,
.minimum_version_id = 1,
.needed = icount_state_needed,
.fields = (VMStateField[]) {
VMSTATE_INT64(qemu_icount_bias, TimersState),
VMSTATE_INT64(qemu_icount, TimersState),
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription * []) {
&icount_vmstate_warp_timer,
&icount_vmstate_adjust_timers,
&icount_vmstate_shift,
NULL
}
};
static const VMStateDescription vmstate_timers = {
.name = "timer",
.version_id = 2,
.minimum_version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_INT64(cpu_ticks_offset, TimersState),
VMSTATE_UNUSED(8),
VMSTATE_INT64_V(cpu_clock_offset, TimersState, 2),
VMSTATE_END_OF_LIST()
},
.subsections = (const VMStateDescription * []) {
&icount_vmstate_timers,
NULL
}
};
static void do_nothing(CPUState *cpu, run_on_cpu_data unused)
{
}
void qemu_timer_notify_cb(void *opaque, QEMUClockType type)
{
if (!icount_enabled() || type != QEMU_CLOCK_VIRTUAL) {
qemu_notify_event();
return;
}
if (qemu_in_vcpu_thread()) {
/*
* A CPU is currently running; kick it back out to the
* tcg_cpu_exec() loop so it will recalculate its
* icount deadline immediately.
*/
qemu_cpu_kick(current_cpu);
} else if (first_cpu) {
/*
* qemu_cpu_kick is not enough to kick a halted CPU out of
* qemu_tcg_wait_io_event. async_run_on_cpu, instead,
* causes cpu_thread_is_idle to return false. This way,
* handle_icount_deadline can run.
* If we have no CPUs at all for some reason, we don't
* need to do anything.
*/
async_run_on_cpu(first_cpu, do_nothing, RUN_ON_CPU_NULL);
}
}
TimersState timers_state;
/* initialize timers state and the cpu throttle for convenience */
void cpu_timers_init(void)
{
seqlock_init(&timers_state.vm_clock_seqlock);
qemu_spin_init(&timers_state.vm_clock_lock);
vmstate_register(NULL, 0, &vmstate_timers, &timers_state);
cpu_throttle_init();
}
softmmu/cpus.c
+7 -737
View File
File diff suppressed because it is too large Load Diff
softmmu/icount.c
+492
View File
@@ -0,0 +1,492 @@
/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
*
* 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 "qemu/cutils.h"
#include "migration/vmstate.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "exec/exec-all.h"
#include "sysemu/cpus.h"
#include "sysemu/qtest.h"
#include "qemu/main-loop.h"
#include "qemu/option.h"
#include "qemu/seqlock.h"
#include "sysemu/replay.h"
#include "sysemu/runstate.h"
#include "hw/core/cpu.h"
#include "sysemu/cpu-timers.h"
#include "sysemu/cpu-throttle.h"
#include "timers-state.h"
/*
* ICOUNT: Instruction Counter
*
* this module is split off from cpu-timers because the icount part
* is TCG-specific, and does not need to be built for other accels.
*/
static bool icount_sleep = true;
/* Arbitrarily pick 1MIPS as the minimum allowable speed. */
#define MAX_ICOUNT_SHIFT 10
/*
* 0 = Do not count executed instructions.
* 1 = Fixed conversion of insn to ns via "shift" option
* 2 = Runtime adaptive algorithm to compute shift
*/
int use_icount;
static void icount_enable_precise(void)
{
use_icount = 1;
}
static void icount_enable_adaptive(void)
{
use_icount = 2;
}
/*
* The current number of executed instructions is based on what we
* originally budgeted minus the current state of the decrementing
* icount counters in extra/u16.low.
*/
static int64_t cpu_get_icount_executed(CPUState *cpu)
{
return (cpu->icount_budget -
(cpu_neg(cpu)->icount_decr.u16.low + cpu->icount_extra));
}
/*
* Update the global shared timer_state.qemu_icount to take into
* account executed instructions. This is done by the TCG vCPU
* thread so the main-loop can see time has moved forward.
*/
static void cpu_update_icount_locked(CPUState *cpu)
{
int64_t executed = cpu_get_icount_executed(cpu);
cpu->icount_budget -= executed;
qatomic_set_i64(&timers_state.qemu_icount,
timers_state.qemu_icount + executed);
}
/*
* Update the global shared timer_state.qemu_icount to take into
* account executed instructions. This is done by the TCG vCPU
* thread so the main-loop can see time has moved forward.
*/
void cpu_update_icount(CPUState *cpu)
{
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
cpu_update_icount_locked(cpu);
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
static int64_t cpu_get_icount_raw_locked(void)
{
CPUState *cpu = current_cpu;
if (cpu && cpu->running) {
if (!cpu->can_do_io) {
error_report("Bad icount read");
exit(1);
}
/* Take into account what has run */
cpu_update_icount_locked(cpu);
}
/* The read is protected by the seqlock, but needs atomic64 to avoid UB */
return qatomic_read_i64(&timers_state.qemu_icount);
}
static int64_t cpu_get_icount_locked(void)
{
int64_t icount = cpu_get_icount_raw_locked();
return qatomic_read_i64(&timers_state.qemu_icount_bias) +
cpu_icount_to_ns(icount);
}
int64_t cpu_get_icount_raw(void)
{
int64_t icount;
unsigned start;
do {
start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
icount = cpu_get_icount_raw_locked();
} while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
return icount;
}
/* Return the virtual CPU time, based on the instruction counter. */
int64_t cpu_get_icount(void)
{
int64_t icount;
unsigned start;
do {
start = seqlock_read_begin(&timers_state.vm_clock_seqlock);
icount = cpu_get_icount_locked();
} while (seqlock_read_retry(&timers_state.vm_clock_seqlock, start));
return icount;
}
int64_t cpu_icount_to_ns(int64_t icount)
{
return icount << qatomic_read(&timers_state.icount_time_shift);
}
/*
* Correlation between real and virtual time is always going to be
* fairly approximate, so ignore small variation.
* When the guest is idle real and virtual time will be aligned in
* the IO wait loop.
*/
#define ICOUNT_WOBBLE (NANOSECONDS_PER_SECOND / 10)
static void icount_adjust(void)
{
int64_t cur_time;
int64_t cur_icount;
int64_t delta;
/* Protected by TimersState mutex. */
static int64_t last_delta;
/* If the VM is not running, then do nothing. */
if (!runstate_is_running()) {
return;
}
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
cur_time = REPLAY_CLOCK_LOCKED(REPLAY_CLOCK_VIRTUAL_RT,
cpu_get_clock_locked());
cur_icount = cpu_get_icount_locked();
delta = cur_icount - cur_time;
/* FIXME: This is a very crude algorithm, somewhat prone to oscillation. */
if (delta > 0
&& last_delta + ICOUNT_WOBBLE < delta * 2
&& timers_state.icount_time_shift > 0) {
/* The guest is getting too far ahead. Slow time down. */
qatomic_set(&timers_state.icount_time_shift,
timers_state.icount_time_shift - 1);
}
if (delta < 0
&& last_delta - ICOUNT_WOBBLE > delta * 2
&& timers_state.icount_time_shift < MAX_ICOUNT_SHIFT) {
/* The guest is getting too far behind. Speed time up. */
qatomic_set(&timers_state.icount_time_shift,
timers_state.icount_time_shift + 1);
}
last_delta = delta;
qatomic_set_i64(&timers_state.qemu_icount_bias,
cur_icount - (timers_state.qemu_icount
<< timers_state.icount_time_shift));
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
}
static void icount_adjust_rt(void *opaque)
{
timer_mod(timers_state.icount_rt_timer,
qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + 1000);
icount_adjust();
}
static void icount_adjust_vm(void *opaque)
{
timer_mod(timers_state.icount_vm_timer,
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
NANOSECONDS_PER_SECOND / 10);
icount_adjust();
}
int64_t qemu_icount_round(int64_t count)
{
int shift = qatomic_read(&timers_state.icount_time_shift);
return (count + (1 << shift) - 1) >> shift;
}
static void icount_warp_rt(void)
{
unsigned seq;
int64_t warp_start;
/*
* The icount_warp_timer is rescheduled soon after vm_clock_warp_start
* changes from -1 to another value, so the race here is okay.
*/
do {
seq = seqlock_read_begin(&timers_state.vm_clock_seqlock);
warp_start = timers_state.vm_clock_warp_start;
} while (seqlock_read_retry(&timers_state.vm_clock_seqlock, seq));
if (warp_start == -1) {
return;
}
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (runstate_is_running()) {
int64_t clock = REPLAY_CLOCK_LOCKED(REPLAY_CLOCK_VIRTUAL_RT,
cpu_get_clock_locked());
int64_t warp_delta;
warp_delta = clock - timers_state.vm_clock_warp_start;
if (icount_enabled() == 2) {
/*
* In adaptive mode, do not let QEMU_CLOCK_VIRTUAL run too
* far ahead of real time.
*/
int64_t cur_icount = cpu_get_icount_locked();
int64_t delta = clock - cur_icount;
warp_delta = MIN(warp_delta, delta);
}
qatomic_set_i64(&timers_state.qemu_icount_bias,
timers_state.qemu_icount_bias + warp_delta);
}
timers_state.vm_clock_warp_start = -1;
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (qemu_clock_expired(QEMU_CLOCK_VIRTUAL)) {
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
}
}
static void icount_timer_cb(void *opaque)
{
/*
* No need for a checkpoint because the timer already synchronizes
* with CHECKPOINT_CLOCK_VIRTUAL_RT.
*/
icount_warp_rt();
}
void qemu_start_warp_timer(void)
{
int64_t clock;
int64_t deadline;
assert(icount_enabled());
/*
* Nothing to do if the VM is stopped: QEMU_CLOCK_VIRTUAL timers
* do not fire, so computing the deadline does not make sense.
*/
if (!runstate_is_running()) {
return;
}
if (replay_mode != REPLAY_MODE_PLAY) {
if (!all_cpu_threads_idle()) {
return;
}
if (qtest_enabled()) {
/* When testing, qtest commands advance icount. */
return;
}
replay_checkpoint(CHECKPOINT_CLOCK_WARP_START);
} else {
/* warp clock deterministically in record/replay mode */
if (!replay_checkpoint(CHECKPOINT_CLOCK_WARP_START)) {
/*
* vCPU is sleeping and warp can't be started.
* It is probably a race condition: notification sent
* to vCPU was processed in advance and vCPU went to sleep.
* Therefore we have to wake it up for doing someting.
*/
if (replay_has_checkpoint()) {
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
}
return;
}
}
/* We want to use the earliest deadline from ALL vm_clocks */
clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
~QEMU_TIMER_ATTR_EXTERNAL);
if (deadline < 0) {
static bool notified;
if (!icount_sleep && !notified) {
warn_report("icount sleep disabled and no active timers");
notified = true;
}
return;
}
if (deadline > 0) {
/*
* Ensure QEMU_CLOCK_VIRTUAL proceeds even when the virtual CPU goes to
* sleep. Otherwise, the CPU might be waiting for a future timer
* interrupt to wake it up, but the interrupt never comes because
* the vCPU isn't running any insns and thus doesn't advance the
* QEMU_CLOCK_VIRTUAL.
*/
if (!icount_sleep) {
/*
* We never let VCPUs sleep in no sleep icount mode.
* If there is a pending QEMU_CLOCK_VIRTUAL timer we just advance
* to the next QEMU_CLOCK_VIRTUAL event and notify it.
* It is useful when we want a deterministic execution time,
* isolated from host latencies.
*/
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
qatomic_set_i64(&timers_state.qemu_icount_bias,
timers_state.qemu_icount_bias + deadline);
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
} else {
/*
* We do stop VCPUs and only advance QEMU_CLOCK_VIRTUAL after some
* "real" time, (related to the time left until the next event) has
* passed. The QEMU_CLOCK_VIRTUAL_RT clock will do this.
* This avoids that the warps are visible externally; for example,
* you will not be sending network packets continuously instead of
* every 100ms.
*/
seqlock_write_lock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
if (timers_state.vm_clock_warp_start == -1
|| timers_state.vm_clock_warp_start > clock) {
timers_state.vm_clock_warp_start = clock;
}
seqlock_write_unlock(&timers_state.vm_clock_seqlock,
&timers_state.vm_clock_lock);
timer_mod_anticipate(timers_state.icount_warp_timer,
clock + deadline);
}
} else if (deadline == 0) {
qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
}
}
void qemu_account_warp_timer(void)
{
if (!icount_enabled() || !icount_sleep) {
return;
}
/*
* Nothing to do if the VM is stopped: QEMU_CLOCK_VIRTUAL timers
* do not fire, so computing the deadline does not make sense.
*/
if (!runstate_is_running()) {
return;
}
/* warp clock deterministically in record/replay mode */
if (!replay_checkpoint(CHECKPOINT_CLOCK_WARP_ACCOUNT)) {
return;
}
timer_del(timers_state.icount_warp_timer);
icount_warp_rt();
}
void configure_icount(QemuOpts *opts, Error **errp)
{
const char *option = qemu_opt_get(opts, "shift");
bool sleep = qemu_opt_get_bool(opts, "sleep", true);
bool align = qemu_opt_get_bool(opts, "align", false);
long time_shift = -1;
if (!option) {
if (qemu_opt_get(opts, "align") != NULL) {
error_setg(errp, "Please specify shift option when using align");
}
return;
}
if (align && !sleep) {
error_setg(errp, "align=on and sleep=off are incompatible");
return;
}
if (strcmp(option, "auto") != 0) {
if (qemu_strtol(option, NULL, 0, &time_shift) < 0
|| time_shift < 0 || time_shift > MAX_ICOUNT_SHIFT) {
error_setg(errp, "icount: Invalid shift value");
return;
}
} else if (icount_align_option) {
error_setg(errp, "shift=auto and align=on are incompatible");
return;
} else if (!icount_sleep) {
error_setg(errp, "shift=auto and sleep=off are incompatible");
return;
}
icount_sleep = sleep;
if (icount_sleep) {
timers_state.icount_warp_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL_RT,
icount_timer_cb, NULL);
}
icount_align_option = align;
if (time_shift >= 0) {
timers_state.icount_time_shift = time_shift;
icount_enable_precise();
return;
}
icount_enable_adaptive();
/*
* 125MIPS seems a reasonable initial guess at the guest speed.
* It will be corrected fairly quickly anyway.
*/
timers_state.icount_time_shift = 3;
/*
* Have both realtime and virtual time triggers for speed adjustment.
* The realtime trigger catches emulated time passing too slowly,
* the virtual time trigger catches emulated time passing too fast.
* Realtime triggers occur even when idle, so use them less frequently
* than VM triggers.
*/
timers_state.vm_clock_warp_start = -1;
timers_state.icount_rt_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL_RT,
icount_adjust_rt, NULL);
timer_mod(timers_state.icount_rt_timer,
qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL_RT) + 1000);
timers_state.icount_vm_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
icount_adjust_vm, NULL);
timer_mod(timers_state.icount_vm_timer,
qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
NANOSECONDS_PER_SECOND / 10);
}
softmmu/meson.build
+8 -2
View File
@@ -1,4 +1,4 @@
specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files(
specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: [files(
'arch_init.c',
'balloon.c',
'cpus.c',
@@ -7,4 +7,10 @@ specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files(
'memory.c',
'memory_mapping.c',
'qtest.c',
'vl.c'))
'vl.c',
'cpu-timers.c',
)])
specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TCG'], if_true: [files(
'icount.c'
)])

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