[Tcpreplay-users] (no subject)

[Shai R. <sh...@cs...>]

Hi there,

I'm using Linux version 2.4.18-27.7 (Red-hat Linux 7.3)
I'm trying: ./tcpreplay -R -i eth3 <file name>

After doing:
echo 32768 /proc/sys/net/core/wmem_default
echo 32768  /proc/sys/net/core/wmem_max
echo 32768  /proc/sys/net/core/rmem_max
echo 32768  /proc/sys/net/core/rmem_default

I get:
1337777 packets (307917628 bytes) sent in 29 seconds
10310110.0 bytes/sec 78.66 megabits/sec 44793 packets/sec

However if I set:

echo 524287  /proc/sys/net/core/wmem_default
echo 524287  /proc/sys/net/core/wmem_max                                         
echo 524287  /proc/sys/net/core/rmem_max                                         
echo 524287  /proc/sys/net/core/rmem_default                                     

I get:
 1337777 packets (307917628 bytes) sent in 29 seconds
 10553665.0 bytes/sec 80.52 megabits/sec 45851 packets/sec
 1221653 write attempts failed from full buffers and were repeated

Two questions:
1. How it can happen that with a smaller buffer I'm getting zero write
failures, while with a larger  buffer I'm getting almost 92% write
failures.

2. How it can be that more than  90% of the
writes fail but the overall throughput is higher?

Thanks

Shai