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From: "Denis V. Lunev" <den@openvz.org>
To: Jason Wang <jasowang@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>,
	qemu-devel@nongnu.org, Vincenzo Maffione <v.maffione@gmail.com>
Subject: Re: [Qemu-devel] [PATCH for 2.5 1/1] e1000: fix hang of win2k12 shutdown with flood ping
Date: Fri, 27 Nov 2015 14:42:03 +0300	[thread overview]
Message-ID: <5658418B.6000700@openvz.org> (raw)
In-Reply-To: <5657FD3A.407@openvz.org>

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.maffione@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 <den@openvz.org>
>> CC: Vincenzo Maffione <v.maffione@gmail.com>
>> CC: Stefan Hajnoczi <stefanha@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

  reply	other threads:[~2015-11-27 11:42 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-27  6:48 [Qemu-devel] [PATCH for 2.5 1/1] e1000: fix hang of win2k12 shutdown with flood ping Denis V. Lunev
2015-11-27  6:50 ` Denis V. Lunev
2015-11-27 11:42   ` Denis V. Lunev [this message]
2015-11-30  5:58     ` Jason Wang
2015-11-30  6:22       ` Denis V. Lunev
2015-12-01  3:31         ` Jason Wang
2015-12-01  9:38           ` Denis V. Lunev
2015-12-02  5:06             ` Jason Wang
2015-12-03 14:43               ` Peter Maydell

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