From patchwork Mon Mar 14 07:44:47 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Dovgalyuk X-Patchwork-Id: 8576941 Return-Path: X-Original-To: patchwork-qemu-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 498F79F54C for ; Mon, 14 Mar 2016 07:46:52 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5CC012045A for ; Mon, 14 Mar 2016 07:46:51 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 39A0B20462 for ; Mon, 14 Mar 2016 07:46:50 +0000 (UTC) Received: from localhost ([::1]:39485 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afNDF-0004LK-Mc for patchwork-qemu-devel@patchwork.kernel.org; Mon, 14 Mar 2016 03:46:49 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52965) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afNBK-000157-St for qemu-devel@nongnu.org; Mon, 14 Mar 2016 03:44:52 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1afNBJ-0003tk-9w for qemu-devel@nongnu.org; Mon, 14 Mar 2016 03:44:50 -0400 Received: from mail.ispras.ru ([83.149.199.45]:50481) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1afNBI-0003tb-U6 for qemu-devel@nongnu.org; Mon, 14 Mar 2016 03:44:49 -0400 Received: from [10.10.150.45] (unknown [85.142.117.224]) by mail.ispras.ru (Postfix) with ESMTPSA id 13DF354007B; Mon, 14 Mar 2016 10:44:48 +0300 (MSK) To: qemu-devel@nongnu.org From: Pavel Dovgalyuk Date: Mon, 14 Mar 2016 10:44:47 +0300 Message-ID: <20160314074447.4980.43294.stgit@PASHA-ISP> In-Reply-To: <20160314074429.4980.34777.stgit@PASHA-ISP> References: <20160314074429.4980.34777.stgit@PASHA-ISP> User-Agent: StGit/0.16 MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 83.149.199.45 Cc: edgar.iglesias@xilinx.com, peter.maydell@linaro.org, igor.rubinov@gmail.com, alex.bennee@linaro.org, mark.burton@greensocs.com, real@ispras.ru, hines@cert.org, batuzovk@ispras.ru, maria.klimushenkova@ispras.ru, pavel.dovgaluk@ispras.ru, pbonzini@redhat.com, kwolf@redhat.com, stefanha@redhat.com, fred.konrad@greensocs.com Subject: [Qemu-devel] [PATCH v5 3/7] icount: decouple warp calls 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=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY autolearn=unavailable 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 qemu_clock_warp function is called to update virtual clock when CPU is sleeping. This function includes replay checkpoint to make execution deterministic in icount mode. Record/replay module flushes async event queue at checkpoints. Some of the events (e.g., block devices operations) include interaction with hardware. E.g., APIC polled by block devices sets one of IRQ flags. Flag to be set depends on currently executed thread (CPU or iothread). Therefore in replay mode we have to process the checkpoints in the same thread as they were recorded. qemu_clock_warp function (and its checkpoint) may be called from different thread. This patch decouples two different execution cases of this function: call when CPU is sleeping from iothread and call from cpu thread to update virtual clock. First task is performed by qemu_start_warp_timer function. It sets warp timer event to the moment of nearest pending virtual timer. Second function (qemu_account_warp_timer) is called from cpu thread before execution of the code. It advances virtual clock by adding the length of period while CPU was sleeping. Signed-off-by: Pavel Dovgalyuk --- cpus.c | 53 +++++++++++++++++++++++++++-------------------- docs/replay.txt | 17 +++++++++++---- include/qemu/timer.h | 14 +++++++++--- include/sysemu/replay.h | 3 ++- main-loop.c | 2 +- qemu-timer.c | 4 +++- stubs/clock-warp.c | 2 +- 7 files changed, 60 insertions(+), 35 deletions(-) diff --git a/cpus.c b/cpus.c index 85d0f87..3ab9e04 100644 --- a/cpus.c +++ b/cpus.c @@ -373,6 +373,7 @@ static void icount_warp_rt(void) static void icount_dummy_timer(void *opaque) { (void)opaque; + icount_warp_rt(); } void qtest_clock_warp(int64_t dest) @@ -396,17 +397,12 @@ void qtest_clock_warp(int64_t dest) qemu_clock_notify(QEMU_CLOCK_VIRTUAL); } -void qemu_clock_warp(QEMUClockType type) +void qemu_start_warp_timer(void) { int64_t clock; int64_t deadline; - /* - * There are too many global variables to make the "warp" behavior - * applicable to other clocks. But a clock argument removes the - * need for if statements all over the place. - */ - if (type != QEMU_CLOCK_VIRTUAL || !use_icount) { + if (!use_icount) { return; } @@ -418,29 +414,17 @@ void qemu_clock_warp(QEMUClockType type) } /* warp clock deterministically in record/replay mode */ - if (!replay_checkpoint(CHECKPOINT_CLOCK_WARP)) { + if (!replay_checkpoint(CHECKPOINT_CLOCK_WARP_START)) { return; } - if (icount_sleep) { - /* - * If the CPUs have been sleeping, advance QEMU_CLOCK_VIRTUAL timer now. - * This ensures that the deadline for the timer is computed correctly - * below. - * This also makes sure that the insn counter is synchronized before - * the CPU starts running, in case the CPU is woken by an event other - * than the earliest QEMU_CLOCK_VIRTUAL timer. - */ - icount_warp_rt(); - timer_del(icount_warp_timer); - } if (!all_cpu_threads_idle()) { return; } if (qtest_enabled()) { /* When testing, qtest commands advance icount. */ - return; + return; } /* We want to use the earliest deadline from ALL vm_clocks */ @@ -496,6 +480,31 @@ void qemu_clock_warp(QEMUClockType type) } } +void qemu_account_warp_timer(void) +{ + int64_t clock; + int64_t warp_delta; + + if (!use_icount || !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(icount_warp_timer); + icount_warp_rt(); +} + static bool icount_state_needed(void *opaque) { return use_icount; @@ -1496,7 +1505,7 @@ static void tcg_exec_all(void) int r; /* Account partial waits to QEMU_CLOCK_VIRTUAL. */ - qemu_clock_warp(QEMU_CLOCK_VIRTUAL); + qemu_account_warp_timer(); if (next_cpu == NULL) { next_cpu = first_cpu; diff --git a/docs/replay.txt b/docs/replay.txt index 149727e..cf13cef 100644 --- a/docs/replay.txt +++ b/docs/replay.txt @@ -134,11 +134,18 @@ of time. That's why we do not process a group of timers until the checkpoint event will be read from the log. Such an event allows synchronizing CPU execution and timer events. -Another checkpoints application in record/replay is instruction counting -while the virtual machine is idle. This function (qemu_clock_warp) is called -from the wait loop. It changes virtual machine state and must be deterministic -then. That is why we added checkpoint to this function to prevent its -operation in replay mode when it does not correspond to record mode. +Two other checkpoints govern the "warping" of the virtual clock. While +the virtual machine is idle, the virtual clock increments at 1 ns per +*real time* nanosecond. This is done by setting up a timer (called the +warp timer) and then incrementing the virtual clock (called "warping" +the virtual clock) as soon as the CPUs need to go out of the idle state. +These actions change virtual machine state and must be deterministic. +Two functions are used for this purpose, and each of them creates a +checkpoint. qemu_start_warp_timer checks if the CPUs are idle and if so +starts accounting real time to virtual clock. qemu_account_warp_timer +is called when the CPUs get an interrupt or when a virtual clock timer +fires, and it warps the virtual clock by the amount of real time that +has passed since qemu_start_warp_timer. Bottom halves ------------- diff --git a/include/qemu/timer.h b/include/qemu/timer.h index d0946cb..21ffec6 100644 --- a/include/qemu/timer.h +++ b/include/qemu/timer.h @@ -210,12 +210,18 @@ void qemu_clock_notify(QEMUClockType type); void qemu_clock_enable(QEMUClockType type, bool enabled); /** - * qemu_clock_warp: - * @type: the clock type + * qemu_start_warp_timer: + * + * Starts a timer for virtual clock update + */ +void qemu_start_warp_timer(void); + +/** + * qemu_account_warp_timer: * - * Warp a clock to a new value + * Updates virtual clock for the time CPU was sleeping */ -void qemu_clock_warp(QEMUClockType type); +void qemu_account_warp_timer(void); /** * qemu_clock_register_reset_notifier: diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h index d24d502..e798919 100644 --- a/include/sysemu/replay.h +++ b/include/sysemu/replay.h @@ -27,7 +27,8 @@ typedef enum ReplayClockKind ReplayClockKind; /* IDs of the checkpoints */ enum ReplayCheckpoint { - CHECKPOINT_CLOCK_WARP, + CHECKPOINT_CLOCK_WARP_START, + CHECKPOINT_CLOCK_WARP_ACCOUNT, CHECKPOINT_RESET_REQUESTED, CHECKPOINT_SUSPEND_REQUESTED, CHECKPOINT_CLOCK_VIRTUAL, diff --git a/main-loop.c b/main-loop.c index 19beae7..3a7f4cd 100644 --- a/main-loop.c +++ b/main-loop.c @@ -509,7 +509,7 @@ int main_loop_wait(int nonblocking) /* CPU thread can infinitely wait for event after missing the warp */ - qemu_clock_warp(QEMU_CLOCK_VIRTUAL); + qemu_start_warp_timer(); qemu_clock_run_all_timers(); return ret; diff --git a/qemu-timer.c b/qemu-timer.c index e98ecc9..4441fe6 100644 --- a/qemu-timer.c +++ b/qemu-timer.c @@ -394,7 +394,9 @@ static bool timer_mod_ns_locked(QEMUTimerList *timer_list, static void timerlist_rearm(QEMUTimerList *timer_list) { /* Interrupt execution to force deadline recalculation. */ - qemu_clock_warp(timer_list->clock->type); + if (timer_list->clock->type == QEMU_CLOCK_VIRTUAL) { + qemu_start_warp_timer(); + } timerlist_notify(timer_list); } diff --git a/stubs/clock-warp.c b/stubs/clock-warp.c index 5ae32b9..8acb58a 100644 --- a/stubs/clock-warp.c +++ b/stubs/clock-warp.c @@ -2,7 +2,7 @@ #include "qemu-common.h" #include "qemu/timer.h" -void qemu_clock_warp(QEMUClockType type) +void qemu_start_warp_timer(void) { }