From patchwork Thu Jan 17 17:10:25 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfgang Mauerer X-Patchwork-Id: 213326 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id C7F302C007B for ; Fri, 18 Jan 2013 04:10:43 +1100 (EST) Received: from localhost ([::1]:36065 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TvszB-0008Oh-UA for incoming@patchwork.ozlabs.org; Thu, 17 Jan 2013 12:10:41 -0500 Received: from eggs.gnu.org ([208.118.235.92]:57650) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tvsyz-0008Az-Sy for qemu-devel@nongnu.org; Thu, 17 Jan 2013 12:10:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Tvsyy-0002WY-E7 for qemu-devel@nongnu.org; Thu, 17 Jan 2013 12:10:29 -0500 Received: from gecko.sbs.de ([194.138.37.40]:29818) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Tvsyy-0002WN-5J for qemu-devel@nongnu.org; Thu, 17 Jan 2013 12:10:28 -0500 Received: from mail2.sbs.de (localhost [127.0.0.1]) by gecko.sbs.de (8.13.6/8.13.6) with ESMTP id r0HHARWF006299; Thu, 17 Jan 2013 18:10:27 +0100 Received: from dirichlet.erls.siemens.de (dirichlet.erls.siemens.de [146.254.15.38] (may be forged)) by mail2.sbs.de (8.13.6/8.13.6) with ESMTP id r0HHARqm029809; Thu, 17 Jan 2013 18:10:27 +0100 From: Wolfgang Mauerer To: sw@weilnetz.de Date: Thu, 17 Jan 2013 18:10:25 +0100 Message-Id: <1358442625-30828-1-git-send-email-wolfgang.mauerer@siemens.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <50F06EF3.9070200@weilnetz.de> References: <50F06EF3.9070200@weilnetz.de> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x X-Received-From: 194.138.37.40 Cc: aliguori@us.ibm.com, Wolfgang Mauerer , qemu-devel@nongnu.org Subject: [Qemu-devel] [[PATCH v2]] Add option to slow qemu down X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 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 For slow targets and fast hosts, the emulation may be faster than the actual hardware, which can be undesirable for various reasons. Add a run-time option to slow down the emulation by sleeping in the CPU emulation. Signed-off-by: Wolfgang Mauerer --- cpus.c | 29 +++++++++++++++++++++++++++++ include/qemu-common.h | 2 ++ qemu-options.hx | 14 ++++++++++++++ vl.c | 10 ++++++++++ 4 files changed, 55 insertions(+), 0 deletions(-) diff --git a/cpus.c b/cpus.c index a4390c3..eae10f4 100644 --- a/cpus.c +++ b/cpus.c @@ -61,6 +61,7 @@ #endif /* CONFIG_LINUX */ static CPUArchState *next_cpu; +static bool use_slowdown = false; static bool cpu_thread_is_idle(CPUArchState *env) { @@ -106,6 +107,8 @@ static QEMUTimer *icount_warp_timer; static int64_t vm_clock_warp_start; static int64_t qemu_icount; +static double slowdown_factor; + typedef struct TimersState { int64_t cpu_ticks_prev; int64_t cpu_ticks_offset; @@ -385,6 +388,20 @@ void configure_icount(const char *option) qemu_get_clock_ns(vm_clock) + get_ticks_per_sec() / 10); } +void configure_slowdown(const char *option) +{ + if (!option) { + return; + } + + slowdown_factor = strtod(option, NULL)/100.0; + /* We cannot provide speedups, obviously */ + if (slowdown_factor < 0) + slowdown_factor *= -1.0; + + use_slowdown = true; +} + /***********************************************************/ void hw_error(const char *fmt, ...) { @@ -1094,6 +1111,8 @@ void vm_stop_force_state(RunState state) static int tcg_cpu_exec(CPUArchState *env) { int ret; + int64_t ss; + uint64_t slowdown_sleep; #ifdef CONFIG_PROFILER int64_t ti; #endif @@ -1114,7 +1133,17 @@ static int tcg_cpu_exec(CPUArchState *env) env->icount_decr.u16.low = decr; env->icount_extra = count; } + if (use_slowdown) { + ss = qemu_get_clock_ns(rt_clock); + } + ret = cpu_exec(env); + + if (use_slowdown) { + slowdown_sleep = qemu_get_clock_ns(rt_clock) - ss; + slowdown_sleep *= slowdown_factor; + g_usleep(slowdown_sleep/1024); + } #ifdef CONFIG_PROFILER qemu_time += profile_getclock() - ti; #endif diff --git a/include/qemu-common.h b/include/qemu-common.h index ca464bb..652abb9 100644 --- a/include/qemu-common.h +++ b/include/qemu-common.h @@ -119,6 +119,8 @@ static inline char *realpath(const char *path, char *resolved_path) void configure_icount(const char *option); extern int use_icount; +void configure_slowdown(const char *option); + /* FIXME: Remove NEED_CPU_H. */ #ifndef NEED_CPU_H diff --git a/qemu-options.hx b/qemu-options.hx index 40cd683..d5eb5eb 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -2667,6 +2667,20 @@ order cores with complex cache hierarchies. The number of instructions executed often has little or no correlation with actual performance. ETEXI +DEF("slowdown", HAS_ARG, QEMU_OPTION_slowdown, \ + "-slowdown s \n" \ + " Slow down the CPU emulation by (approximately) s percent\n", + QEMU_ARCH_ALL) +STEXI +@item -slowdown @var{s} +@findex -slowdown +Slow down the virtual CPU by approximately s percent (i.e., for c time +units of execution time, sleep for c*s/100 time units). This makes it +possible to align the emulated machine's performance roughly with +the performance of physical entities, but does not provide identical +performance profiles since the emulation is not cycle accurate. +ETEXI + DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \ "-watchdog i6300esb|ib700\n" \ " enable virtual hardware watchdog [default=none]\n", diff --git a/vl.c b/vl.c index 8ce2b10..9aa44e0 100644 --- a/vl.c +++ b/vl.c @@ -2713,6 +2713,7 @@ int main(int argc, char **argv, char **envp) int i; int snapshot, linux_boot; const char *icount_option = NULL; + const char *slowdown_option = NULL; const char *initrd_filename; const char *kernel_filename, *kernel_cmdline; char boot_devices[33] = ""; @@ -3607,6 +3608,9 @@ int main(int argc, char **argv, char **envp) case QEMU_OPTION_icount: icount_option = optarg; break; + case QEMU_OPTION_slowdown: + slowdown_option = optarg; + break; case QEMU_OPTION_incoming: incoming = optarg; runstate_set(RUN_STATE_INMIGRATE); @@ -3970,6 +3974,12 @@ int main(int argc, char **argv, char **envp) /* clean up network at qemu process termination */ atexit(&net_cleanup); + if (slowdown_option && (kvm_enabled() || xen_enabled())) { + fprintf(stderr, "-slowdown is not allowed with kvm or xen\n"); + exit(1); + } + configure_slowdown(slowdown_option); + if (net_init_clients() < 0) { exit(1); }