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Mon, 18 Mar 2024 08:47:01 -0700 (PDT) Received: from wheely.local0.net ([118.208.155.46]) by smtp.gmail.com with ESMTPSA id v22-20020a634816000000b005dc26144d96sm7332108pga.75.2024.03.18.08.46.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Mar 2024 08:47:01 -0700 (PDT) From: Nicholas Piggin To: qemu-devel@nongnu.org Cc: Nicholas Piggin , Pavel Dovgalyuk , =?utf-8?q?Philippe_Mathieu-Dau?= =?utf-8?q?d=C3=A9?= , Richard Henderson , =?utf-8?q?Alex_Benn=C3=A9?= =?utf-8?q?e?= , Paolo Bonzini , John Snow , Cleber Rosa , Wainer dos Santos Moschetta , Beraldo Leal , Michael Tokarev Subject: [PATCH v5 05/24] Revert "replay: stop us hanging in rr_wait_io_event" Date: Tue, 19 Mar 2024 01:46:02 +1000 Message-ID: <20240318154621.2361161-6-npiggin@gmail.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20240318154621.2361161-1-npiggin@gmail.com> References: <20240318154621.2361161-1-npiggin@gmail.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::32f; envelope-from=npiggin@gmail.com; helo=mail-ot1-x32f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_HELO_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org This reverts commit 1f881ea4a444ef36a8b6907b0b82be4b3af253a2. That commit causes reverse_debugging.py test failures, and does not seem to solve the root cause of the problem x86-64 still hangs in record/replay tests. The problem with short-cutting the iowait that was taken during record phase is that related events will not get consumed at the same points (e.g., reading the clock). A hang with zero icount always seems to be a symptom of an earlier problem that has caused the recording to become out of synch with the execution and consumption of events by replay. Signed-off-by: Nicholas Piggin Acked-by: Alex Bennée --- include/sysemu/replay.h | 5 ----- accel/tcg/tcg-accel-ops-rr.c | 2 +- replay/replay.c | 21 --------------------- 3 files changed, 1 insertion(+), 27 deletions(-) diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h index f229b2109c..8102fa54f0 100644 --- a/include/sysemu/replay.h +++ b/include/sysemu/replay.h @@ -73,11 +73,6 @@ int replay_get_instructions(void); /*! Updates instructions counter in replay mode. */ void replay_account_executed_instructions(void); -/** - * replay_can_wait: check if we should pause for wait-io - */ -bool replay_can_wait(void); - /* Processing clocks and other time sources */ /*! Save the specified clock */ diff --git a/accel/tcg/tcg-accel-ops-rr.c b/accel/tcg/tcg-accel-ops-rr.c index 894e73e52c..a942442a33 100644 --- a/accel/tcg/tcg-accel-ops-rr.c +++ b/accel/tcg/tcg-accel-ops-rr.c @@ -109,7 +109,7 @@ static void rr_wait_io_event(void) { CPUState *cpu; - while (all_cpu_threads_idle() && replay_can_wait()) { + while (all_cpu_threads_idle()) { rr_stop_kick_timer(); qemu_cond_wait_bql(first_cpu->halt_cond); } diff --git a/replay/replay.c b/replay/replay.c index b8564a4813..895fa6b67a 100644 --- a/replay/replay.c +++ b/replay/replay.c @@ -451,27 +451,6 @@ void replay_start(void) replay_enable_events(); } -/* - * For none/record the answer is yes. - */ -bool replay_can_wait(void) -{ - if (replay_mode == REPLAY_MODE_PLAY) { - /* - * For playback we shouldn't ever be at a point we wait. If - * the instruction count has reached zero and we have an - * unconsumed event we should go around again and consume it. - */ - if (replay_state.instruction_count == 0 && replay_state.has_unread_data) { - return false; - } else { - replay_sync_error("Playback shouldn't have to iowait"); - } - } - return true; -} - - void replay_finish(void) { if (replay_mode == REPLAY_MODE_NONE) {