From patchwork Wed Jul 25 12:16:49 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Dovgalyuk X-Patchwork-Id: 10543973 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B9167112E for ; Wed, 25 Jul 2018 12:35:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A44D629818 for ; Wed, 25 Jul 2018 12:35:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9667129D4F; Wed, 25 Jul 2018 12:35:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 202D929818 for ; Wed, 25 Jul 2018 12:35:39 +0000 (UTC) Received: from localhost ([::1]:49280 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fiJ10-0002AE-AJ for patchwork-qemu-devel@patchwork.kernel.org; Wed, 25 Jul 2018 08:35:38 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39656) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fiIiq-0003IV-0U for qemu-devel@nongnu.org; Wed, 25 Jul 2018 08:16:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fiIim-0006uI-W6 for qemu-devel@nongnu.org; Wed, 25 Jul 2018 08:16:51 -0400 Received: from mail.ispras.ru ([83.149.199.45]:36894) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fiIim-0006sO-Is for qemu-devel@nongnu.org; Wed, 25 Jul 2018 08:16:48 -0400 Received: from [127.0.1.1] (unknown [85.142.117.226]) by mail.ispras.ru (Postfix) with ESMTPSA id 6E05654006B; Wed, 25 Jul 2018 15:16:47 +0300 (MSK) From: Pavel Dovgalyuk To: qemu-devel@nongnu.org Date: Wed, 25 Jul 2018 15:16:49 +0300 Message-ID: <20180725121649.12867.55853.stgit@pasha-VirtualBox> In-Reply-To: <20180725121311.12867.21729.stgit@pasha-VirtualBox> References: <20180725121311.12867.21729.stgit@pasha-VirtualBox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 83.149.199.45 Subject: [Qemu-devel] [PATCH v5 21/24] replay: wake up vCPU when replaying 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: kwolf@redhat.com, peter.maydell@linaro.org, war2jordan@live.com, pavel.dovgaluk@ispras.ru, pbonzini@redhat.com, quintela@redhat.com, ciro.santilli@gmail.com, jasowang@redhat.com, crosthwaite.peter@gmail.com, zuban32s@gmail.com, armbru@redhat.com, maria.klimushenkova@ispras.ru, mst@redhat.com, kraxel@redhat.com, boost.lists@gmail.com, thomas.dullien@googlemail.com, dovgaluk@ispras.ru, mreitz@redhat.com, alex.bennee@linaro.org, dgilbert@redhat.com, rth@twiddle.net Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP In record/replay icount mode vCPU thread and iothread synchronize the execution using the checkpoints. vCPU thread processes the virtual timers and iothread processes all others. When iothread wants to wake up sleeping vCPU thread, it sends dummy queued work. Therefore it could be the following sequence of the events in record mode: - IO: sending dummy work - IO: processing timers - CPU: wakeup - CPU: clearing dummy work - CPU: processing virtual timers But due to the races in replay mode the sequence may change: - IO: sending dummy work - CPU: wakeup - CPU: clearing dummy work - CPU: sleeping again because nothing to do - IO: Processing timers - CPU: zzzz In this case vCPU will not wake up, because dummy work is not to be set up again. This patch tries to wake up the vCPU when it sleeps and the icount warp checkpoint isn't met. It means that vCPU has something to do, because there are no other reasons of non-matching warp checkpoint. Signed-off-by: Pavel Dovgalyuk --- v5: improve checking that vCPU is still sleeping --- cpus.c | 31 +++++++++++++++++++++---------- include/sysemu/replay.h | 3 +++ replay/replay.c | 12 ++++++++++++ 3 files changed, 36 insertions(+), 10 deletions(-) diff --git a/cpus.c b/cpus.c index 181ce33..38bd521 100644 --- a/cpus.c +++ b/cpus.c @@ -539,18 +539,29 @@ void qemu_start_warp_timer(void) return; } - /* warp clock deterministically in record/replay mode */ - if (!replay_checkpoint(CHECKPOINT_CLOCK_WARP_START)) { - return; - } + if (replay_mode != REPLAY_MODE_PLAY) { + if (!all_cpu_threads_idle()) { + return; + } - if (!all_cpu_threads_idle()) { - return; - } + if (qtest_enabled()) { + /* When testing, qtest commands advance icount. */ + 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 */ diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h index a3113c1..8118b00 100644 --- a/include/sysemu/replay.h +++ b/include/sysemu/replay.h @@ -136,6 +136,9 @@ void replay_shutdown_request(ShutdownCause cause); Returns 0 in PLAY mode if checkpoint was not found. Returns 1 in all other cases. */ bool replay_checkpoint(ReplayCheckpoint checkpoint); +/*! Used to determine that checkpoint is pending. + Does not proceed to the next event in the log. */ +bool replay_has_checkpoint(void); /* Asynchronous events queue */ diff --git a/replay/replay.c b/replay/replay.c index dcce902..6e82764 100644 --- a/replay/replay.c +++ b/replay/replay.c @@ -240,6 +240,18 @@ out: return res; } +bool replay_has_checkpoint(void) +{ + bool res = false; + if (replay_mode == REPLAY_MODE_PLAY) { + g_assert(replay_mutex_locked()); + replay_account_executed_instructions(); + res = EVENT_CHECKPOINT <= replay_state.data_kind + && replay_state.data_kind <= EVENT_CHECKPOINT_LAST; + } + return res; +} + static void replay_enable(const char *fname, int mode) { const char *fmode = NULL;