From mboxrd@z Thu Jan 1 00:00:00 1970 From: Xupeng Yun Subject: Re: High latency with VirtIO NIC Date: Thu, 24 Mar 2011 21:45:03 +0800 Message-ID: <76F180B5B89249CDA99A9521558BAF11@gmail.com> References: <750D7880952B4EEF856255153646029D@gmail.com> <4D8B1B4F.5070305@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail-iy0-f174.google.com ([209.85.210.174]:41411 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751634Ab1CXNpa (ORCPT ); Thu, 24 Mar 2011 09:45:30 -0400 Received: by iyb26 with SMTP id 26so9679499iyb.19 for ; Thu, 24 Mar 2011 06:45:30 -0700 (PDT) In-Reply-To: <4D8B1B4F.5070305@redhat.com> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Thursday, March 24, 2011 at 6:22 PM, Avi Kivity wrote: Try vhost-net, that should have much better latencies. > Indeed, the latency is much better after switching to vhost-net, it drops from 3+ms to ~1.5ms on average when there is no network load on the KVM guest, but the latencies become bad again when there is heavy network load on the guest(~70Mbps RX and ~25Mbps TX). --------------------------- ping KVM guest (app211) from the host --------------------------- 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? Thanks, Xupeng