From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59334) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a2Crp-0007yK-BN for qemu-devel@nongnu.org; Fri, 27 Nov 2015 01:50:50 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a2Crl-0006GT-AU for qemu-devel@nongnu.org; Fri, 27 Nov 2015 01:50:49 -0500 Received: from relay.parallels.com ([195.214.232.42]:50549) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a2Crl-0006GN-2H for qemu-devel@nongnu.org; Fri, 27 Nov 2015 01:50:45 -0500 References: <1448606921-17846-1-git-send-email-den@openvz.org> From: "Denis V. Lunev" Message-ID: <5657FD3A.407@openvz.org> Date: Fri, 27 Nov 2015 09:50:34 +0300 MIME-Version: 1.0 In-Reply-To: <1448606921-17846-1-git-send-email-den@openvz.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for 2.5 1/1] e1000: fix hang of win2k12 shutdown with flood ping List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, Vincenzo Maffione On 11/27/2015 09:48 AM, Denis V. Lunev wrote: > 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 > --- > hw/net/e1000.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/hw/net/e1000.c b/hw/net/e1000.c > index c877e06..0af528f 100644 > --- a/hw/net/e1000.c > +++ b/hw/net/e1000.c > @@ -447,6 +447,9 @@ static void e1000_reset(void *opaque) > e1000_link_down(d); > } > > + /* Throttle interrupts to allow poor Win 2012 to shutdown */ > + 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; Intel manual says about ITR that " A initial suggested range is 651-5580 (28Bh - 15CCh)." Should we use something other than 250? :) http://www.intel.com/content/www/us/en/embedded/products/networking/pci-pci-x-family-gbe-controllers-software-dev-manual.html Den