On 12/01/2015 05:38 PM, Denis V. Lunev wrote: > On 12/01/2015 06:31 AM, Jason Wang wrote: >> >> On 11/30/2015 02:22 PM, Denis V. Lunev wrote: >>> On 11/30/2015 08:58 AM, Jason Wang wrote: >>>> On 11/27/2015 07:42 PM, Denis V. Lunev wrote: >>>>> On 11/27/2015 09:50 AM, Denis V. Lunev wrote: >>>>>> 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 <v.maffi...@gmail.com> >>>>>>> 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 <d...@openvz.org> >>>>>>> CC: Vincenzo Maffione <v.maffi...@gmail.com> >>>>>>> CC: Stefan Hajnoczi <stefa...@redhat.com> >>>>>>> --- >>>>>>> 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 >>>>> Jason, can you look to this? >>>>> >>>>> I have rechecked MAINTAINERs file and found that >>>>> I have missed you here. Sorry :( >>>>> >>>>> Den >>>>> >>>> No problem. >>>> >>>> But I have a question. What if ITR is disabled? >>>> >>> On behalf of guest I do not think that this is really true. >>> In this case the guest should set it to a real value and >>> after that clear it. This is not the case - my patch >>> applies on a reset only, i.e. the guest do not care at all >>> on this and the value lives "as is". I think that real card >>> behaves in a similar way, it could not generate interrupts >>> with the speed of any hypervisor, i.e. there is natural >>> limitation which allows to bypass this problem or there >>> is a default value. >>> >>> On behalf of QEMU the question is still here. Fortunately >>> the handle (mitigation flag) is on by default. I think that >>> it exists to preserve compatibility with QEMU 1.6 >>> In a real life nobody will turn it off until the person is >>> know what he is doing ;) >>> >>> Den >> Ok, apply to my -net with minor tweaks and adding a TODO in the comment. >> >> We've met several similar issues in the past, need to consider a >> complete solution in the future otherwise we may still hit something >> like this in the future. >> >> Thanks > thank you. > > Can you pls clarify, will it go to 2.5 or no? > > Den
It will go to 2.5. Plan to include this in my last pull request for 2.5. Thanks
