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[2001:4830:134:3::11]) by mx.google.com with ESMTPS id v70si541463qkl.205.2016.08.11.08.36.16 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 11 Aug 2016 08:36:16 -0700 (PDT) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) client-ip=2001:4830:134:3::11; Authentication-Results: mx.google.com; dkim=fail header.i=@linaro.org; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 2001:4830:134:3::11 as permitted sender) smtp.mailfrom=qemu-devel-bounces+patch=linaro.org@nongnu.org; dmarc=fail (p=NONE dis=NONE) header.from=linaro.org Received: from localhost ([::1]:49200 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXs1o-0005Qr-AD for patch@linaro.org; Thu, 11 Aug 2016 11:36:16 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57526) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXrqe-0003or-Ps for qemu-devel@nongnu.org; Thu, 11 Aug 2016 11:24:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bXrqc-0006du-VS for qemu-devel@nongnu.org; Thu, 11 Aug 2016 11:24:44 -0400 Received: from mail-wm0-x235.google.com ([2a00:1450:400c:c09::235]:35390) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bXrqc-0006dj-Kg for qemu-devel@nongnu.org; Thu, 11 Aug 2016 11:24:42 -0400 Received: by mail-wm0-x235.google.com with SMTP id f65so6282361wmi.0 for ; Thu, 11 Aug 2016 08:24:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=AAyQZP0ShkHtWUJnQNjV6f1RbBL3zttHwmCmR54TcZ8=; b=HVMe6OvHfwLxnCcet88+XhXIJuO/f3DvrkSIUXoFw4R72swGWvI5PY0TokGZFgze7H mcCHaOKQv++YrLK9iK9An2N338A2KIxnZW+PIRMmsw9T+tfjR/x3QsGjhQEdmZMjh679 BBU4JNJarIqTX6N/5j4I4wfr4D5R5NvRS6gEY= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=AAyQZP0ShkHtWUJnQNjV6f1RbBL3zttHwmCmR54TcZ8=; b=YNGW6LUqAeZkCZHObjfpX5c5WqxINZHwpesE9wtcslK8AK1rAdlEs+UpckFhoeBVa8 PEgHPC+S0I5nhr1eev4/4PuLPJgytA0ujpIaUV0xNCiHRhANR7bAK3VjpHzIYs9m468A SfauMyxixhysmpvfOz1Li4YHo/MvsLWPv24jeMRgbRTCzJuSgyIZ89Hr0IEVNoHrH3dU vq+c/SvPQx53FfodBH3/y49JIbndH3jNGwGz6IlXeFps0zT9/Ml9Uhak7PQirf9C4wX6 xFkOg+G4GoHMgNZmzCEDfpQK1B+OJ7yEo1lxgazlEkW9DjWzZyt4vvVxodeVeFsb3PHe QWxg== X-Gm-Message-State: AEkooutd8ZpSfrZG0UVV3Qt5D93QIU693VOFRYKubfTasrbdER9NE3nb8VR88SzJkUI25W7u X-Received: by 10.194.104.106 with SMTP id gd10mr11848957wjb.55.1470929081549; Thu, 11 Aug 2016 08:24:41 -0700 (PDT) Received: from zen.linaro.local ([81.128.185.34]) by smtp.gmail.com with ESMTPSA id n2sm3209944wjd.1.2016.08.11.08.24.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Aug 2016 08:24:31 -0700 (PDT) Received: from zen.linaroharston (localhost [127.0.0.1]) by zen.linaro.local (Postfix) with ESMTP id 3BA3E3E031F; Thu, 11 Aug 2016 16:24:31 +0100 (BST) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: mttcg@listserver.greensocs.com, qemu-devel@nongnu.org, fred.konrad@greensocs.com, a.rigo@virtualopensystems.com, cota@braap.org, bobby.prani@gmail.com, nikunj@linux.vnet.ibm.com Date: Thu, 11 Aug 2016 16:24:14 +0100 Message-Id: <1470929064-4092-19-git-send-email-alex.bennee@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1470929064-4092-1-git-send-email-alex.bennee@linaro.org> References: <1470929064-4092-1-git-send-email-alex.bennee@linaro.org> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a00:1450:400c:c09::235 Subject: [Qemu-devel] [RFC v4 18/28] tcg: remove global exit_request 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: peter.maydell@linaro.org, claudio.fontana@huawei.com, Peter Crosthwaite , jan.kiszka@siemens.com, mark.burton@greensocs.com, serge.fdrv@gmail.com, pbonzini@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , rth@twiddle.net Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" There are now only two uses of the global exit_request left. The first ensures we exit the run_loop when we first start to process pending work and in the kick handler. This is just as easily done by setting the first_cpu->exit_request flag. The second use is in the round robin kick routine. The global exit_request ensured every vCPU would set its local exit_request and cause a full exit of the loop. Now the iothread isn't being held while running we can just rely on the kick handler to push us out as intended. We lightly re-factor the main vCPU thread to ensure cpu->exit_requests cause us to exit the main loop and process any IO requests that might come along. Signed-off-by: Alex Bennée --- v4 - moved to after iothread unlocking patch - needed to remove kick exit_request as well. - remove extraneous cpu->exit_request check - remove stray exit_request setting - remove needless atomic operation --- cpu-exec-common.c | 1 - cpu-exec.c | 9 ++------- cpus.c | 18 ++++++++++-------- include/exec/exec-all.h | 1 - 4 files changed, 12 insertions(+), 17 deletions(-) -- 2.7.4 diff --git a/cpu-exec-common.c b/cpu-exec-common.c index e220ba7..e29cf6d 100644 --- a/cpu-exec-common.c +++ b/cpu-exec-common.c @@ -23,7 +23,6 @@ #include "exec/exec-all.h" #include "exec/memory-internal.h" -bool exit_request; int tcg_pending_threads; /* exit the current TB, but without causing any exception to be raised */ diff --git a/cpu-exec.c b/cpu-exec.c index 317ad8e..d2e8b9e 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -531,9 +531,8 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb, /* Something asked us to stop executing * chained TBs; just continue round the main * loop. Whatever requested the exit will also - * have set something else (eg exit_request or - * interrupt_request) which we will handle - * next time around the loop. But we need to + * have set something else (eg interrupt_request) which we + * will handle next time around the loop. But we need to * ensure the tcg_exit_req read in generated code * comes before the next read of cpu->exit_request * or cpu->interrupt_request. @@ -589,10 +588,6 @@ int cpu_exec(CPUState *cpu) rcu_read_lock(); - if (unlikely(atomic_mb_read(&exit_request))) { - cpu->exit_request = 1; - } - cc->cpu_exec_enter(cpu); /* Calculate difference between guest clock and host clock. diff --git a/cpus.c b/cpus.c index 5ed6dc0..8a40a08 100644 --- a/cpus.c +++ b/cpus.c @@ -1215,7 +1215,6 @@ static CPUState *tcg_current_rr_cpu; static void qemu_cpu_kick_rr_cpu(void) { CPUState *cpu; - atomic_mb_set(&exit_request, 1); do { cpu = atomic_mb_read(&tcg_current_rr_cpu); if (cpu) { @@ -1265,11 +1264,11 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) timer_mod(kick_timer, qemu_tcg_next_kick()); } - /* process any pending work */ - atomic_mb_set(&exit_request, 1); - cpu = first_cpu; + /* process any pending work */ + cpu->exit_request = 1; + while (1) { /* Account partial waits to QEMU_CLOCK_VIRTUAL. */ qemu_account_warp_timer(); @@ -1278,7 +1277,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) cpu = first_cpu; } - for (; cpu != NULL && !exit_request; cpu = CPU_NEXT(cpu)) { + while (cpu && !cpu->exit_request) { atomic_mb_set(&tcg_current_rr_cpu, cpu); qemu_clock_enable(QEMU_CLOCK_VIRTUAL, @@ -1300,12 +1299,15 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) break; } - } /* for cpu.. */ + cpu = CPU_NEXT(cpu); + } /* while (cpu && !cpu->exit_request).. */ + /* Does not need atomic_mb_set because a spurious wakeup is okay. */ atomic_set(&tcg_current_rr_cpu, NULL); - /* Pairs with smp_wmb in qemu_cpu_kick. */ - atomic_mb_set(&exit_request, 0); + if (cpu && cpu->exit_request) { + atomic_mb_set(&cpu->exit_request, 0); + } handle_icount_deadline(); diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 3547dfa..27d1a24 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -409,7 +409,6 @@ extern int singlestep; /* cpu-exec.c, accessed with atomic_mb_read/atomic_mb_set */ extern int tcg_pending_threads; -extern bool exit_request; /** * qemu_work_cond - condition to wait for CPU work items completion