From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: High latency with VirtIO NIC Date: Thu, 24 Mar 2011 16:27:25 +0200 Message-ID: <4D8B54CD.1070602@redhat.com> References: <750D7880952B4EEF856255153646029D@gmail.com> <4D8B1B4F.5070305@redhat.com> <76F180B5B89249CDA99A9521558BAF11@gmail.com> <4D8B5044.1050303@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Xupeng Yun Return-path: Received: from mx1.redhat.com ([209.132.183.28]:31737 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753854Ab1CXO13 (ORCPT ); Thu, 24 Mar 2011 10:27:29 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 03/24/2011 04:24 PM, Xupeng Yun wrote: > On Thu, Mar 24, 2011 at 22:08, Avi Kivity wrote: > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3582 ttl=64 time=3.08 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3583 ttl=64 time=1.10 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3584 ttl=64 time=1.03 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3585 ttl=64 time=3.55 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3586 ttl=64 time=1.29 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3587 ttl=64 time=0.710 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3588 ttl=64 time=64.4 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3589 ttl=64 time=0.271 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3590 ttl=64 time=0.563 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3591 ttl=64 time=1.66 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3592 ttl=64 time=0.939 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3593 ttl=64 time=0.819 ms > >> 64 bytes from app211 (192.168.1.211): icmp_seq=3594 ttl=64 time=16.5 ms > >> > >> --------------------------- ping KVM guest (app211) from the host > >> --------------------------- > >> > >> any idea? > >> > > > > Isn't it normal? With heavy load, packets start to queue. > > > Thank you, if the performance drop (from 0.15ms to 1-64ms) at this > workload is normal, I am okay with it. I don't know if this is exactly the point at which latency should rise; what I'm saying is that it can't remain low at all load levels. -- error compiling committee.c: too many arguments to function