Following link explains usage of "oprofile"
http://www.serpentine.com/blog/2006/12/17/make-linux-performance-analysis-easier-with-oprofile/
Vishal
Devesh Sharma wrote:
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
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