From patchwork Thu Oct 27 15:10:15 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: 687756 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 3t4WK26dj2z9vFK for ; Fri, 28 Oct 2016 02:39:18 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=linaro.org header.i=@linaro.org header.b=BEHUdbXh; dkim-atps=neutral Received: from localhost ([::1]:42358 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bzmlv-00033L-O9 for incoming@patchwork.ozlabs.org; Thu, 27 Oct 2016 11:39:15 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42645) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bzmKs-0004ku-2C for qemu-devel@nongnu.org; Thu, 27 Oct 2016 11:11:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bzmKn-0007ic-FF for qemu-devel@nongnu.org; Thu, 27 Oct 2016 11:11:17 -0400 Received: from mail-wm0-x231.google.com ([2a00:1450:400c:c09::231]:38676) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1bzmKn-0007hd-5B for qemu-devel@nongnu.org; Thu, 27 Oct 2016 11:11:13 -0400 Received: by mail-wm0-x231.google.com with SMTP id n67so50404315wme.1 for ; Thu, 27 Oct 2016 08:11:13 -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=Vz19mgXTOc/AHpy/NUiDwc9dX0nQ1KwMVCvSDZA+Jvg=; b=BEHUdbXhImxhCe4KdZR+BqZ57JaE0INF1Zi2QGngGpg/BmUS3qd7dx+CfDBQ+XM1n+ 5I9iY+QVxglqZIMQhR0L43GZGX7E7rgZdYe4MfKLhmuixFDI/Yw6tJJBIgbYq2G1HYPy XcOqX0YYnKs7ezSrDHLyRY43oaskNfKJVYhjc= 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=Vz19mgXTOc/AHpy/NUiDwc9dX0nQ1KwMVCvSDZA+Jvg=; b=MSmYKfawUCQARGmgNzALLtulpYXG+rLBmhSD3m41EROgSESVvV4H/tTfYNX/5UisG4 4vhUYNpM7KlYYXnHZnexcBFVfH64UI//fuiQ8U+Pii/uV161EF0p9eZ/aPqdfLXItmD+ Eh0YYfQofVowBUao2TZiWMY8B/09XmCE610UL51ebCBBGCsAr48JEbNXVMktiCdSQ1sj fFewmwHTHd6OlUjJVMLKHRAzkqoMo80LJAHTzamIry7K754D6oj1BqWWZftzRnqCUpzW 61eockSgYj4bIzsNHFZlp3OpshQImvFDd3LlWz5fXbQZdRjtru74Dn7LM2cl9Xb8TAVs fkQw== X-Gm-Message-State: ABUngvc3qjf+4ulXMGDBXM07ZfTpPLuffwNH+IdSRALd93DSpUo2asE0P/AWXDSYnns+1xvV X-Received: by 10.28.30.143 with SMTP id e137mr7982215wme.96.1477581072037; Thu, 27 Oct 2016 08:11:12 -0700 (PDT) Received: from zen.linaro.local ([81.128.185.34]) by smtp.gmail.com with ESMTPSA id jx8sm9023253wjc.2.2016.10.27.08.11.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 27 Oct 2016 08:11:11 -0700 (PDT) Received: from zen.linaroharston (localhost [127.0.0.1]) by zen.linaro.local (Postfix) with ESMTP id 80D843E03D1; Thu, 27 Oct 2016 16:11:00 +0100 (BST) From: =?UTF-8?q?Alex=20Benn=C3=A9e?= To: pbonzini@redhat.com Date: Thu, 27 Oct 2016 16:10:15 +0100 Message-Id: <20161027151030.20863-19-alex.bennee@linaro.org> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20161027151030.20863-1-alex.bennee@linaro.org> References: <20161027151030.20863-1-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::231 Subject: [Qemu-devel] [PATCH v5 18/33] 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: mttcg@listserver.greensocs.com, peter.maydell@linaro.org, claudio.fontana@huawei.com, nikunj@linux.vnet.ibm.com, Peter Crosthwaite , jan.kiszka@siemens.com, mark.burton@greensocs.com, a.rigo@virtualopensystems.com, qemu-devel@nongnu.org, cota@braap.org, serge.fdrv@gmail.com, bobby.prani@gmail.com, rth@twiddle.net, =?UTF-8?q?Alex=20Benn=C3=A9e?= , fred.konrad@greensocs.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.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 Reviewed-by: Richard Henderson --- v5 - minor merge conflict with kick patch 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 | 2 -- cpu-exec.c | 9 ++------- cpus.c | 18 ++++++++++-------- include/exec/exec-all.h | 3 --- 4 files changed, 12 insertions(+), 20 deletions(-) diff --git a/cpu-exec-common.c b/cpu-exec-common.c index e2bc053..0504a94 100644 --- a/cpu-exec-common.c +++ b/cpu-exec-common.c @@ -23,8 +23,6 @@ #include "exec/exec-all.h" #include "exec/memory-internal.h" -bool exit_request; - /* exit the current TB, but without causing any exception to be raised */ void cpu_loop_exit_noexc(CPUState *cpu) { diff --git a/cpu-exec.c b/cpu-exec.c index 3ca44bd..3458dd6 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -565,9 +565,8 @@ 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. @@ -623,10 +622,6 @@ 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 6367772..bba71af 100644 --- a/cpus.c +++ b/cpus.c @@ -760,7 +760,6 @@ static inline int64_t qemu_tcg_next_kick(void) 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) { @@ -1282,11 +1281,11 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) start_tcg_kick_timer(); - /* 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(); @@ -1295,7 +1294,7 @@ 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, @@ -1315,12 +1314,15 @@ 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 b8b9989..d097515 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -406,7 +406,4 @@ bool memory_region_is_unassigned(MemoryRegion *mr); /* vl.c */ extern int singlestep; -/* cpu-exec.c, accessed with atomic_mb_read/atomic_mb_set */ -extern bool exit_request; - #endif