Hi,
I upgrading an application to the CONFIG_PACKET_MMAP
interface, and was trying to figure out how the api works. I 'RTFS'
But had a few questions:
1. for tp_frame_size, I dont want to truncate any data on ethernet, I
need 1514 bytes, is this the best way to do it and not waste space?
static const int
TURBO_FRAME_SIZE=TPACKET_ALIGN(TPACKET_ALIGN(sizeof(tpacket_hdr))+TPACKET_ALIGN(sizeof(struct
sockaddr_ll)+ETH_HLEN) + 1500);
2. what is tp_block_nr for? I dont understand it, I just set it to 1
and make tp_block_size big enough for all the frames I need, so its
just one contiguous space, all I need is about a megabyte I think.
3. is this the general approach for the api?
open socket
set ring size
mmap()
h starts at frame[0] of the mmaped area
while(1) {
if (tp->status == 0) poll() for pollin on the socket /* is there a
race here? */
parse/copy out what I want from h + h->tp_mac
set tp->status to 0 when I am done
h = next packet in ring, or wraps
}
4. what does the copy threshold setsockopt tuning accomplish? doesnt it always
have to copy anyway, to the mmaped area?
Thanks,
c.c. me por favor...
K. Lohan
------------------------
kambo at home dawt com
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