RE: [PATCH 2.6.12-rc4] IPv4/IPv6: UDP Large Send Offload feature
From: Ravinandan Arakali <hidden>
Date: 2005-05-27 16:32:00
Hi David, Thanks for the quick feedback. At that time when we considered using skb_shinfo(skb)->fraglist, it contained fragments of MTU size. So, for a 60k udp datagram and 1500 MTU we will have 60k/1500 = 45 fragments which is more than MAX_SKB_FRAGS(18). However we will relook at fraglist for the possibility of increasing frag size to >MTU. Thanks, Ravi -----Original Message----- From: David S. Miller [mailto:davem@davemloft.net] Sent: Thursday, May 26, 2005 4:42 PM To: ravinandan.arakali@neterion.com Cc: jgarzik@pobox.com; netdev@oss.sgi.com; raghavendra.koushik@neterion.com; leonid.grossman@neterion.com; ananda.raju@neterion.com; rapuru.sriram@neterion.com Subject: Re: [PATCH 2.6.12-rc4] IPv4/IPv6: UDP Large Send Offload feature sock_append_data() seems like a lot of wasted work. We already pass around the fragmented SKB as a list chained by skb_shinfo(skb)->fraglist, just pass this thing to the device and in this way you'll avoid all of that work sock_append_data() does entirely. Or is there a reason you did not implement it this way? This is one of the uses the skb_shinfo(skb)->fraglist was intended for. IN FACT, this fragmentation offload you are implementing here is what the feature bit NETIF_F_FRAGLIST was meant to indicate.