From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KOaco-0005II-An for qemu-devel@nongnu.org; Thu, 31 Jul 2008 12:03:34 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KOacm-0005Gz-BE for qemu-devel@nongnu.org; Thu, 31 Jul 2008 12:03:33 -0400 Received: from [199.232.76.173] (port=43031 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KOacm-0005Gq-4j for qemu-devel@nongnu.org; Thu, 31 Jul 2008 12:03:32 -0400 Received: from an-out-0708.google.com ([209.85.132.250]:29129) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1KOacm-00034l-3n for qemu-devel@nongnu.org; Thu, 31 Jul 2008 12:03:32 -0400 Received: by an-out-0708.google.com with SMTP id d18so182214and.130 for ; Thu, 31 Jul 2008 09:03:30 -0700 (PDT) Message-ID: <4891E230.8090109@codemonkey.ws> Date: Thu, 31 Jul 2008 11:02:56 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <4891DF28.6040908@cisco.com> In-Reply-To: <4891DF28.6040908@cisco.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: scheduling of qemu threads Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "David S. Ahern" Cc: qemu-devel@nongnu.org David S. Ahern wrote: > Last week or so Anthony made a comment about qemu basically being single > threaded given its global mutex. What are the impacts to simultaneous > scheduling of qemu threads? As I understand it, qemu has a main thread, > a monitor thread, an IO thread and a thread for each vcpu. Can 2 or more > vcpu threads run concurrently? Can a vcpu thread and an IO thread run > concurrently? Does kvm alter the concurrency? > All threads run in lock-step except when a VCPU is running (via kvm_run). So a VCPU can run while the IO thread is active. Only one VCPU can execute IO at a given time though. Regards, Anthony Liguori > david >