From patchwork Fri Jun 3 20:40:22 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Alex_Benn=C3=A9e?= X-Patchwork-Id: 630015 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3rLx7V4Yvzz9t8P for ; Sat, 4 Jun 2016 06:50:30 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b=Qe+VPBil; dkim-atps=neutral Received: from localhost ([::1]:57678 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b8w32-0001Nb-DS for incoming@patchwork.ozlabs.org; Fri, 03 Jun 2016 16:50:28 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37546) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b8vte-00006G-Lj for qemu-devel@nongnu.org; Fri, 03 Jun 2016 16:40:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b8vtc-0000ZE-6I for qemu-devel@nongnu.org; Fri, 03 Jun 2016 16:40:45 -0400 Received: from mail-wm0-x22c.google.com ([2a00:1450:400c:c09::22c]:35789) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b8vtb-0000Yo-Nw for qemu-devel@nongnu.org; Fri, 03 Jun 2016 16:40:44 -0400 Received: by mail-wm0-x22c.google.com with SMTP id a136so12049938wme.0 for ; Fri, 03 Jun 2016 13:40:43 -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=CGxzm/tree1Pt7CkqsjF8lXlHIznqZn7RyOZRlYIsHM=; b=Qe+VPBilFrG1zaDn6Jc+dLWOSxJpfHZyewg100c753fEMORkpxdQxUiwQBimjji2yd Kzn7GYqQVW99uzgJhlH3HfMUAuk0dC2dOWzkGcug7qogO35QUukN16yd4NV4P3TlAm9L NHIqQe3OwKLVCaI/c4GqQuJOh7TU7n1828zPc= 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=CGxzm/tree1Pt7CkqsjF8lXlHIznqZn7RyOZRlYIsHM=; b=BCSkrcUe4r1JZ8Jt7KzzDW8SWXtXvmiTwd7DctpapaT8BYcv1IdOpIOqgIhYiRb+ir zwWzxP1CcZJxtIU5PrFOx+pOmn5Mvyu2f5PiCe3pAbqW7/L82dV/GNpIqSYk+8mhYf/8 CODoNU1WQLzRg4YV09apUY/xdrHn987cmrWlQeiFXKJQIwbDRd+2eCb8IQd8StFhoMzW qjxfaybMyMjZorYhRDfOJHy5AZrGYRTJyWlID4pawg3mCSn+gAwDotoWmuBnF5/Wqnr8 vJCu8Y9E2B5CfTFhSfKCVvTE+DygVm1Z8rXmL91lpiz0m4NhyYrYnbR21yNEPnYXAxmK XnfA== X-Gm-Message-State: ALyK8tLiZrVfGc8gRauo+NhUOTCIlQxE4ooLtArFxhZ8nR0+Efbk8a9KlykcV0aX4v8q8FP5 X-Received: by 10.28.212.198 with SMTP id l189mr1185227wmg.100.1464986443017; Fri, 03 Jun 2016 13:40:43 -0700 (PDT) Received: from zen.linaro.local ([81.128.185.34]) by smtp.gmail.com with ESMTPSA id k62sm1233883wmb.7.2016.06.03.13.40.33 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Jun 2016 13:40:37 -0700 (PDT) Received: from zen.linaroharston (localhost [127.0.0.1]) by zen.linaro.local (Postfix) with ESMTP id 3D7973E302F; Fri, 3 Jun 2016 21:40:40 +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, serge.fdrv@gmail.com, cota@braap.org, bobby.prani@gmail.com Date: Fri, 3 Jun 2016 21:40:22 +0100 Message-Id: <1464986428-6739-14-git-send-email-alex.bennee@linaro.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1464986428-6739-1-git-send-email-alex.bennee@linaro.org> References: <1464986428-6739-1-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::22c Subject: [Qemu-devel] [RFC v3 13/19] tcg: rename tcg_current_cpu to tcg_current_rr_cpu 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, Peter Crosthwaite , claudio.fontana@huawei.com, mark.burton@greensocs.com, jan.kiszka@siemens.com, pbonzini@redhat.com, =?UTF-8?q?Alex=20Benn=C3=A9e?= , rth@twiddle.net Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" ..and make the definition local to cpus. In preparation for MTTCG the concept of a global tcg_current_cpu will no longer make sense. However we still need to keep track of it in the single-threaded case to be able to exit quickly when required. qemu_cpu_kick_no_halt() moves and becomes qemu_cpu_kick_rr_cpu() to emphasise its use-case. qemu_cpu_kick now kicks the relevant cpu as well as qemu_kick_rr_cpu() which will become a no-op in MTTCG. Signed-off-by: Alex Bennée --- cpu-exec-common.c | 1 - cpu-exec.c | 3 --- cpus.c | 41 ++++++++++++++++++++++++----------------- include/exec/exec-all.h | 2 -- 4 files changed, 24 insertions(+), 23 deletions(-) diff --git a/cpu-exec-common.c b/cpu-exec-common.c index 132cd03..f42d24a 100644 --- a/cpu-exec-common.c +++ b/cpu-exec-common.c @@ -24,7 +24,6 @@ #include "exec/memory-internal.h" bool exit_request; -CPUState *tcg_current_cpu; /* exit the current TB from a signal handler. The host registers are restored in a state compatible with the CPU emulator diff --git a/cpu-exec.c b/cpu-exec.c index ae81e8e..68e804b 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -597,7 +597,6 @@ int cpu_exec(CPUState *cpu) return EXCP_HALTED; } - atomic_mb_set(&tcg_current_cpu, cpu); rcu_read_lock(); if (unlikely(atomic_mb_read(&exit_request))) { @@ -658,7 +657,5 @@ int cpu_exec(CPUState *cpu) /* fail safe : never use current_cpu outside cpu_exec() */ current_cpu = NULL; - /* Does not need atomic_mb_set because a spurious wakeup is okay. */ - atomic_set(&tcg_current_cpu, NULL); return ret; } diff --git a/cpus.c b/cpus.c index 12e04c9..a139ad3 100644 --- a/cpus.c +++ b/cpus.c @@ -942,6 +942,7 @@ void run_on_cpu(CPUState *cpu, void (*func)(void *data), void *data) { struct qemu_work_item wi; + /* Always true when using tcg RR scheduling from a vCPU context */ if (qemu_cpu_is_self(cpu)) { func(data); return; @@ -1216,15 +1217,29 @@ static int tcg_cpu_exec(CPUState *cpu) * This is done explicitly rather than relying on side-effects * elsewhere. */ -static void qemu_cpu_kick_no_halt(void); #define TCG_KICK_FREQ (qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + \ NANOSECONDS_PER_SECOND / 10) +/* only used in single-thread tcg mode */ +static CPUState *tcg_current_rr_cpu; + +/* Kick the currently round-robin scheduled vCPU */ +static void qemu_cpu_kick_rr_cpu(void) +{ + CPUState *cpu; + do { + cpu = atomic_mb_read(&tcg_current_rr_cpu); + if (cpu) { + cpu_exit(cpu); + } + } while (cpu != atomic_mb_read(&tcg_current_rr_cpu)); +} + static void kick_tcg_thread(void *opaque) { QEMUTimer *self = *(QEMUTimer **) opaque; timer_mod(self, TCG_KICK_FREQ); - qemu_cpu_kick_no_halt(); + qemu_cpu_kick_rr_cpu(); } static void *qemu_tcg_cpu_thread_fn(void *arg) @@ -1275,6 +1290,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) } for (; cpu != NULL && !exit_request; cpu = CPU_NEXT(cpu)) { + atomic_mb_set(&tcg_current_rr_cpu, cpu); qemu_clock_enable(QEMU_CLOCK_VIRTUAL, (cpu->singlestep_enabled & SSTEP_NOTIMER) == 0); @@ -1290,6 +1306,8 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) } } /* for cpu.. */ + /* 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); @@ -1326,24 +1344,13 @@ static void qemu_cpu_kick_thread(CPUState *cpu) #endif } -static void qemu_cpu_kick_no_halt(void) -{ - CPUState *cpu; - /* Ensure whatever caused the exit has reached the CPU threads before - * writing exit_request. - */ - atomic_mb_set(&exit_request, 1); - cpu = atomic_mb_read(&tcg_current_cpu); - if (cpu) { - cpu_exit(cpu); - } -} - void qemu_cpu_kick(CPUState *cpu) { qemu_cond_broadcast(cpu->halt_cond); if (tcg_enabled()) { - qemu_cpu_kick_no_halt(); + cpu_exit(cpu); + /* Also ensure current RR cpu is kicked */ + qemu_cpu_kick_rr_cpu(); } else { qemu_cpu_kick_thread(cpu); } @@ -1384,7 +1391,7 @@ void qemu_mutex_lock_iothread(void) atomic_dec(&iothread_requesting_mutex); } else { if (qemu_mutex_trylock(&qemu_global_mutex)) { - qemu_cpu_kick_no_halt(); + qemu_cpu_kick_rr_cpu(); qemu_mutex_lock(&qemu_global_mutex); } atomic_dec(&iothread_requesting_mutex); diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index e30f02b..31f4c38 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -405,8 +405,6 @@ bool memory_region_is_unassigned(MemoryRegion *mr); /* vl.c */ extern int singlestep; -/* cpu-exec.c, accessed with atomic_mb_read/atomic_mb_set */ -extern CPUState *tcg_current_cpu; extern bool exit_request; #endif