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replay: recording and replaying clock ticks

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Clock ticks are considered as the sources of non-deterministic data for
virtual machine. This patch implements saving the clock values when they
are acquired (virtual, host clock).
When replaying the execution corresponding values are read from log and
transfered to the module, which wants to read the values.
Such a design required the clock polling to be synchronized. Sometimes
it is not true - e.g. when timeouts for timer lists are checked. In this case
we use a cached value of the clock, passing it to the client code.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20150917162427.8676.36558.stgit@PASHA-ISP.def.inno>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
This commit is contained in:
Pavel Dovgalyuk 2015-09-17 19:24:28 +03:00 • committed by Paolo Bonzini
parent c0c071d052
commit 8eda206e09
7 changed files with 119 additions and 4 deletions
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8
qemu-timer.c
View file

@ -24,6 +24,7 @@
#include "qemu/main-loop.h"
#include "qemu/timer.h"
#include "sysemu/replay.h"
#ifdef CONFIG_POSIX
#include <pthread.h>
@ -570,15 +571,16 @@ int64_t qemu_clock_get_ns(QEMUClockType type)
return cpu_get_clock();
}
case QEMU_CLOCK_HOST:
now = get_clock_realtime();
now = REPLAY_CLOCK(REPLAY_CLOCK_HOST, get_clock_realtime());
last = clock->last;
clock->last = now;
if (now < last || now > (last + get_max_clock_jump())) {
if ((now < last || now > (last + get_max_clock_jump()))
&& replay_mode == REPLAY_MODE_NONE) {
notifier_list_notify(&clock->reset_notifiers, &now);
}
return now;
case QEMU_CLOCK_VIRTUAL_RT:
return cpu_get_clock();
return REPLAY_CLOCK(REPLAY_CLOCK_VIRTUAL_RT, cpu_get_clock());
}
}