On Tue, Apr 21, 2009 at 9:48 PM, Michael Blizek <michi1@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > Hi! > > On 18:37 Tue 21 Apr , Devesh Sharma wrote: >> Hello michi, Sorry for late reply. comments are inline: > > ... > >> > Is there any packet loss on the link? What does "ping -f" and >> packet loss is very less......after data transfer in TBits I observer >> on 5 tx packet drops >> > "ping -f -s 4096" say? How much does the latency increase if you send >> > bigger packets? Is there a "magic value" which causes a "sudden increase" >> > (e.g. 4051 is much slower than 4050)? >> Yes there is a magic number for packet size of 4040 bytes in ping -s >> 4040 gives proper results >> but of ping -s 4041 every alternate packet get delayed upto 1000 ms. > > This is interesting: > Ethernet header is 14 byte + 4 byte crc32 (you said, you are using something > else, do you know the header/trailer size?) There is no additional header or trailer to the packet. Its posted to my device as given to hard_start_xmit this is actually an InfiniBand over our proprietary network so its an IPoIB interface. > IP header is 20 byte > UDP header is 8 byte (what prococol are you using?) I am using TCP not UDP > --- > 54 bytes > > 4040+54 = 4094 > I have also checked with my device debugging tool, it posting exactly 2 descriptors each of 2048 size for every 4040 byte ping packet, so for (4096-4040) = 56 additional bytes. > This is very close to the 4096 page size most machines have. But 1000 ms for > a 8KB continuous memory allocation on a machine with 64GB RAM sounds pretty > extreme. Maybe oprofile has has clues or there was a regression and older > kernels run faster? How to use oprofile with this? Interrupt handling of my device may also be a bottle neck? I am also not able to receive jeffrey's posts!! > > -Michi > -- > programing a layer 3+4 network protocol for mesh networks > see http://michaelblizek.twilightparadox.com > > -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
