From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55508) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a5mRi-0003vU-I7 for qemu-devel@nongnu.org; Sun, 06 Dec 2015 22:26:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a5mRe-0003vT-Hx for qemu-devel@nongnu.org; Sun, 06 Dec 2015 22:26:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42977) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a5mRe-0003vK-D2 for qemu-devel@nongnu.org; Sun, 06 Dec 2015 22:26:34 -0500 From: Jason Wang Date: Mon, 7 Dec 2015 11:26:05 +0800 Message-Id: <1449458773-7141-2-git-send-email-jasowang@redhat.com> In-Reply-To: <1449458773-7141-1-git-send-email-jasowang@redhat.com> References: <1449458773-7141-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PULL for 2.5 1/9] e1000: fix hang of win2k12 shutdown with flood ping List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: peter.maydell@linaro.org, qemu-devel@nongnu.org Cc: "Denis V. Lunev" , Jason Wang , Stefan Hajnoczi , Vincenzo Maffione From: "Denis V. Lunev" e1000 driver in Win2k12 is really well rotten. It 100% hangs on shutdown of UP VM under flood ping. The guest checks card state and reinjects itself interrupt in a loop. This is fatal for UP machine. There is no good way to fix this misbehavior but to kludge it. The emulation has interrupt throttling register aka ITR which limits interrupt rate and allows the guest to proceed this phase. There is no problem with this kludge for Linux guests - it adjust the value of it itself. On the other hand according to the initial research in commit e9845f0985f088dd01790f4821026df0afba5795 Author: Vincenzo Maffione Date: Fri Aug 2 18:30:52 2013 +0200 e1000: add interrupt mitigation support ... Interrupt mitigation boosts performance when the guest suffers from an high interrupt rate (i.e. receiving short UDP packets at high packet rate). For some numerical results see the following link http://info.iet.unipi.it/~luigi/papers/20130520-rizzo-vm.pdf this should also boost performance a bit. See https://bugzilla.redhat.com/show_bug.cgi?id=874406 for additional details. Signed-off-by: Denis V. Lunev CC: Vincenzo Maffione CC: Stefan Hajnoczi Signed-off-by: Jason Wang --- hw/net/e1000.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/hw/net/e1000.c b/hw/net/e1000.c index c877e06..bec06e9 100644 --- a/hw/net/e1000.c +++ b/hw/net/e1000.c @@ -447,6 +447,11 @@ static void e1000_reset(void *opaque) e1000_link_down(d); } + /* Throttle interrupts to prevent guest (e.g Win 2012) from + * reinjecting interrupts endlessly. TODO: fix non ITR case. + */ + d->mac_reg[ITR] = 250; + /* Some guests expect pre-initialized RAH/RAL (AddrValid flag + MACaddr) */ d->mac_reg[RA] = 0; d->mac_reg[RA + 1] = E1000_RAH_AV; -- 2.5.0