On 18 May 2015, at 17:55, David Vrabel <david.vra...@citrix.com> wrote:
> On 12/05/15 18:18, Joao Martins wrote:
>> Instead of grant/revoking the buffer related to the skb, it will use
>> an already granted page and memcpy to it. The grants will be mapped
>> by xen-netback and reused overtime, but only unmapped when the vif
>> disconnects, as opposed to every packet.
>>
>> This only happens if the backend supports persistent grants since it
>> would, otherwise, introduce the overhead of a memcpy on top of the
>> grant map.
> [...]
>> --- a/drivers/net/xen-netfront.c
>> +++ b/drivers/net/xen-netfront.c
> [...]
>> @@ -1610,7 +1622,10 @@ static int xennet_init_queue(struct netfront_queue
>> *queue)
>> for (i = 0; i < NET_TX_RING_SIZE; i++) {
>> skb_entry_set_link(&queue->tx_skbs[i], i+1);
>> queue->grant_tx[i].ref = GRANT_INVALID_REF;
>> - queue->grant_tx[i].page = NULL;
>> + if (queue->info->feature_persistent)
>> + queue->grant_tx[i].page = alloc_page(GFP_NOIO);
>
> Need to check for alloc failure here and unwind correctly?
Sorry, I overlooked this check. I will fix that.
> Why NOIO?
May be I am misusing NOIO where I meant __GFP_WAIT.
Tough given we are under rtnl_lock() perhaps GFP_ATOMIC should be used
instead.--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
