From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: Number of threads for virtual machine process Date: Tue, 17 Feb 2015 07:51:56 +0100 Message-ID: <54E2E50C.5010409@redhat.com> References: <54E21203.90800@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: mad Engineer Return-path: Received: from mail-wg0-f54.google.com ([74.125.82.54]:51764 "EHLO mail-wg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751787AbbBQGwB (ORCPT ); Tue, 17 Feb 2015 01:52:01 -0500 Received: by mail-wg0-f54.google.com with SMTP id y19so33178896wgg.13 for ; Mon, 16 Feb 2015 22:52:00 -0800 (PST) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 17/02/2015 05:44, mad Engineer wrote: > Thanks for the response. > Can a vm process create any number of extra threads based > on i/o requirement ,or is there any relation between number of VCPU > allowed and these extra threads. No, there is not relation. The I/O threads are created by QEMU, which is a userspace program that uses KVM. Different implementations could do I/O in a different way. Alternatively, QEMU itself can use the Linux AIO API. In that case it still creates threads to do fdatasync, but not to do read/write. > I hope these threads are for disk i/o and for network it uses > vhost-'pid' process. For network it can use vhost or do everything into the main thread of QEMU. Paolo