From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: Performance regression with virtio_net Date: Thu, 27 Jul 2017 23:38:52 +0300 Message-ID: <20170727233244-mutt-send-email-mst@kernel.org> References: <20170727170942.ub24lwgrl3x2outp@ubuntu-hedt> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jason Wang , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org To: Seth Forshee Return-path: Received: from mx1.redhat.com ([209.132.183.28]:50358 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751554AbdG0Uix (ORCPT ); Thu, 27 Jul 2017 16:38:53 -0400 Content-Disposition: inline In-Reply-To: <20170727170942.ub24lwgrl3x2outp@ubuntu-hedt> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Jul 27, 2017 at 12:09:42PM -0500, Seth Forshee wrote: > I'm seeing a performance regression with virtio_net that looks to have > started in 4.12-rc1. I only see it in one context though, downloading > snap packages from the Ubuntu snap store. For example: > > https://api.snapcraft.io/api/v1/snaps/download/b8X2psL1ryVrPt5WEmpYiqfr5emixTd7_1797.snap > > which redirects to Internap's CDN. Normally this downloads in a few > seconds at ~10 MB/s, but with 4.12 and 4.13 it takes minutes with a rate > of ~150 KB/s. Everything else I've tried downloads as normal speeds. So just wget that URL should be enough? > I bisected this to 680557cf79f8 "virtio_net: rework mergeable buffer > handling". If I revert this on top of 4.13-rc2 (along with other changes > needed to successfully revert it) speeds return to normal. > > Thanks, > Seth Interesting. A more likely suspect would be e377fcc8486d40867c6c217077ad0fa40977e060 - could you please try reverting that one instead? Also, could you please look at mergeable_rx_buffer_size in sysfs with and without the change? -- MST