Messages in this thread | | | Date | Wed, 18 Apr 2001 08:04:35 -0400 | From | kambo@home ... | Subject | CONFIG_PACKET_MMAP help |
| |
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
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |