Date: Wed, 25 Nov 2015 14:28:05 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Lan Tianyu <tianyu.lan@intel.com>
Cc: a.motakis@virtualopensystems.com, alex.williamson@redhat.com,
        b.reynal@virtualopensystems.com, bhelgaas@google.com,
        carolyn.wyborny@intel.com, donald.c.skidmore@intel.com,
        eddie.dong@intel.com, nrupal.jani@intel.com, agraf@suse.de,
        kvm@vger.kernel.org, pbonzini@redhat.com, qemu-devel@nongnu.org,
        emil.s.tantilov@intel.com, gerlitz.or@gmail.com,
        mark.d.rustad@intel.com, eric.auger@linaro.org,
        intel-wired-lan@lists.osuosl.org, jeffrey.t.kirsher@intel.com,
        jesse.brandeburg@intel.com, john.ronciak@intel.com,
        linux-api@vger.kernel.org, linux-kernel@vger.kernel.org,
        matthew.vick@intel.com, mitch.a.williams@intel.com,
        netdev@vger.kernel.org, shannon.nelson@intel.com,
        weiyang@linux.vnet.ibm.com, zajec5@gmail.com
Subject: Re: [RFC PATCH V2 3/3] Ixgbevf: Add migration support for ixgbevf
 driver
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On Wed, Nov 25, 2015 at 01:39:32PM +0800, Lan Tianyu wrote:
> On 2015年11月25日 05:20, Michael S. Tsirkin wrote:
> > I have to say, I was much more interested in the idea
> > of tracking dirty memory. I have some thoughts about
> > that one - did you give up on it then?
> 
> No, our finial target is to keep VF active before doing
> migration and tracking dirty memory is essential. But this
> seems not easy to do that in short term for upstream. As
> starters, stop VF before migration.

Frankly, I don't really see what this short term hack buys us,
and if it goes in, we'll have to maintain it forever.

Also, assuming you just want to do ifdown/ifup for some reason, it's
easy enough to do using a guest agent, in a completely generic way.


> After deep thinking, the way of stopping VF still needs tracking
> DMA-accessed dirty memory to make sure the received data buffer
> before stopping VF migrated. It's easier to do that via dummy writing
> data buffer when receive packet.
> 
> 
> -- 
> Best regards
> Tianyu Lan
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