From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: performance regression in virtio-net in 2.6.32-rc4 Date: Mon, 26 Oct 2009 20:48:35 +0200 Message-ID: <20091026184835.GB26473@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, netdev@vger.kernel.org To: Rusty Russell Return-path: Received: from mx1.redhat.com ([209.132.183.28]:22801 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753934AbZJZSvX (ORCPT ); Mon, 26 Oct 2009 14:51:23 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: Hi! I noticed a performance regression in virtio net: going from 2.6.31 to 2.6.32-rc4 I see this, for guest to host communication: [mst@tuck ~]$ ssh robin sh streamtest1 TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.0.0.3 (11.0.0.3) port 0 AF_INET : demo Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.20 7806.48 [mst@tuck ~]$ ssh robin sh streamtest1 TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 11.0.0.3 (11.0.0.3) port 0 AF_INET : demo Recv Send Send Socket Socket Message Elapsed Size Size Size Time Throughput bytes bytes bytes secs. 10^6bits/sec 87380 16384 16384 10.00 6814.60 Note: I had to revert 48925e372f04f5e35fec6269127c62b2c71ab794, and I applied a patch virtio-pci: fix per-vq MSI-X request logic which fixes a bug introduced by f68d24082e22ccee3077d11aeb6dc5354f0ca7f1. Any tips on debugging this? -- MST