From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43000) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ujp99-0006Sk-UU for qemu-devel@nongnu.org; Tue, 04 Jun 2013 07:11:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ujp93-0003Hb-La for qemu-devel@nongnu.org; Tue, 04 Jun 2013 07:11:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16912) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ujp93-0003HV-Cs for qemu-devel@nongnu.org; Tue, 04 Jun 2013 07:11:17 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r54BBGEC003179 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 4 Jun 2013 07:11:16 -0400 Date: Tue, 4 Jun 2013 14:11:49 +0300 From: "Michael S. Tsirkin" Message-ID: <20130604111149.GA13602@redhat.com> References: <20130527093425.GC6120@t430s.nay.redhat.com> <20130527091011.1a8bf205@redhat.com> <20130527092428.0ce3581d@redhat.com> <20130527224304.GA1822@t430s.nay.redhat.com> <20130528082556.2deb1095@redhat.com> <20130530135441.GA21440@redhat.com> <20130531003528.GA4322@t430s.nay.redhat.com> <20130531030254.GB4322@t430s.nay.redhat.com> <20130604064311.GA7204@t430s.nay.redhat.com> <20130604074219.GA17624@t430s.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130604074219.GA17624@t430s.nay.redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 1/2] net: introduce MAC_TABLE_CHANGED event List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Amos Kong Cc: qemu-devel@nongnu.org, stefanha@redhat.com, Luiz Capitulino On Tue, Jun 04, 2013 at 03:42:19PM +0800, Amos Kong wrote: > On Tue, Jun 04, 2013 at 02:43:11PM +0800, Amos Kong wrote: > > > > > > I did more tests in clear environment, and found that the guest hang/slow > > (no response from monitor) is caused by flooding events. I could not > > reproduce it with upstream qemu [1] > > > > If I set event_throttle to 1 ~ 1000, the problem doesn't occur. > > > > It's easier to reproduce this problem by changing vlan config, > > not because it passes more data with VQ cmd, but it will cause more > > events. > > > > > > In this case, we can set event_throttle to 1 for _RX_FILTER_CHANGED > > event to avoid it slows guest. The 1 ms delay should be acceptabled? > > Just discussed with mst in IRC. > > Here we have two problem: > (1) huge number of events will flood monitor client (management), > (2) emitting huge number of events will slow guest itself. > > Both the flag (nc->rxfilter_notify_enabled) and event_throttle API > can be used to avoid problem (1). > > Event_throttle API can clearly avoid problem (2). > > In real testing, I found it's difficult to reproduce problem (2) if we > already use the flag. It seems response time is larger enough, some > events will be dropped, guest could not be slowed. > > Michael told me that we have many ways to slow guest itself, so it's > not a big issue here. > > We care about the delay of responsing event, so we should only use > control flag (As my patch v4). > > What's your opinion? Sounds reasonable. Pls send v3 and we'll discuss :)