RE: [PATCH v13 10/16] Add a hook to intercept external buffers from NIC driver.
I have addressed this issue in v14 patch set. Thanks Xiaohui >-Original Message- >From: David Miller [mailto:da...@davemloft.net] >Sent: Saturday, October 30, 2010 4:29 AM >To: Xin, Xiaohui >Cc: net...@vger.kernel.org; kvm@vger.kernel.org; linux-ker...@vger.kernel.org; >m...@redhat.com; mi...@elte.hu; herb...@gondor.apana.org.au; >jd...@linux.intel.com >Subject: Re: [PATCH v13 10/16] Add a hook to intercept external buffers from >NIC driver. > >From: "Xin, Xiaohui" >Date: Wed, 27 Oct 2010 09:33:12 +0800 > >> Somehow, it seems not a trivial work to support it now. Can we support it >> later and as a todo with our current work? > >I would prefer the feature work properly, rather than only in specific >cases, before being integated. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v13 10/16] Add a hook to intercept external buffers from NIC driver.
From: "Xin, Xiaohui" Date: Wed, 27 Oct 2010 09:33:12 +0800 > Somehow, it seems not a trivial work to support it now. Can we support it > later and as a todo with our current work? I would prefer the feature work properly, rather than only in specific cases, before being integated. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
RE: [PATCH v13 10/16] Add a hook to intercept external buffers from NIC driver.
>-Original Message-
>From: David Miller [mailto:da...@davemloft.net]
>Sent: Tuesday, October 19, 2010 11:24 PM
>To: Xin, Xiaohui
>Cc: net...@vger.kernel.org; kvm@vger.kernel.org; linux-ker...@vger.kernel.org;
>m...@redhat.com; mi...@elte.hu; herb...@gondor.apana.org.au;
>jd...@linux.intel.com
>Subject: Re: [PATCH v13 10/16] Add a hook to intercept external buffers from
>NIC driver.
>
>From: xiaohui@intel.com
>Date: Fri, 15 Oct 2010 17:12:11 +0800
>
>> @@ -2891,6 +2922,11 @@ static int __netif_receive_skb(struct sk_buff *skb)
>> ncls:
>> #endif
>>
>> +/* To intercept mediate passthru(zero-copy) packets here */
>> +skb = handle_mpassthru(skb, &pt_prev, &ret, orig_dev);
>> +if (!skb)
>> +goto out;
>> +
>> /* Handle special case of bridge or macvlan */
>> rx_handler = rcu_dereference(skb->dev->rx_handler);
>> if (rx_handler) {
>
>If you consume the packet here, devices in passthru mode cannot
>be use with bonding.
>
>But there is nothing that prevents a bond being created with such
>a device.
>
>So we have to either prevent such configurations (bad) or make
>it work somehow (good) :-)
The big picture may like this:
To prevent such configurations, we should add code to check in both
mp and bonding driver. If a nic is in zero-copy mode , bonding can't
be made with it, and if nic is in bonding mode, we can't bind the device
to do zero-copy.
If we want to support such configurations, it also has some constraints.
If bonding is created first, we need code to check if all the slaves support
zero-copy mode, and if yes, all the slaves should be assigned a same
page_ctor(), all the packets received should be intercepted with master nic.
If not, fails.
If zero-copy is enabled first, bonding created with it should fail.
Somehow, it seems not a trivial work to support it now. Can we support it
later and as a todo with our current work?
Thanks
Xiaohui
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Re: [PATCH v13 10/16] Add a hook to intercept external buffers from NIC driver.
From: xiaohui@intel.com
Date: Fri, 15 Oct 2010 17:12:11 +0800
> @@ -2891,6 +2922,11 @@ static int __netif_receive_skb(struct sk_buff *skb)
> ncls:
> #endif
>
> + /* To intercept mediate passthru(zero-copy) packets here */
> + skb = handle_mpassthru(skb, &pt_prev, &ret, orig_dev);
> + if (!skb)
> + goto out;
> +
> /* Handle special case of bridge or macvlan */
> rx_handler = rcu_dereference(skb->dev->rx_handler);
> if (rx_handler) {
If you consume the packet here, devices in passthru mode cannot
be use with bonding.
But there is nothing that prevents a bond being created with such
a device.
So we have to either prevent such configurations (bad) or make
it work somehow (good) :-)
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