Re: [PATCH V5 2/6 net-next] netdevice.h: Add zero-copy flag in netdevice

Michał Mirosław
2011-05-17T22:58:00Z

W dniu 18 maja 2011 00:28 użytkownik Shirley Ma <mashirle@us.ibm.com> napisał:
> On Tue, 2011-05-17 at 23:48 +0200, Michał Mirosław wrote:
>> 2011/5/17 Shirley Ma <mashirle@us.ibm.com>:
>> > Looks like to use a new flag requires more time/work. I am thinking
>> > whether we can just use HIGHDMA flag to enable zero-copy in macvtap
>> to
>> > avoid the new flag for now since mavctap uses real NICs as lower
>> device?
>>
>> Is there any other restriction besides requiring driver to not recycle
>> the skb? Are there any drivers that recycle TX skbs?
> Not more other restrictions, skb clone is OK. pskb_expand_head() looks
> OK to me from code review.

> Currently there is no drivers recycle TX skbs.

So why do you require the target device to have some flags at all?

Do I understand correctly, that this zero-copy feature is about
packets received from VMs?

Best Regards,
Michał Mirosław