E4500 spend one core to saturate 1Gbit/s link with TCP -- is it nornal?

[Lev Serebryakov]

Hello, Eugene.
You wrote 21 декабря 2010 г., 9:19:46:


>>>>  Is it normal, that 2.2GHz core is needed to saturate 1Gib link with
>>>>  only one client (and one TCP connction), or I have something
>>>>  misconfigured?
>>> Compare with ftpd that uses sendfile() kernel function.
>>   simple  "iperf"  shows almost same load (slightly less, but it shows
>>   slightly less speed, about 800Mbit).
>> 
> iperf is bad tool IMHO, it abuses gettimeofday() system call and wastes too much CPU time.
> Compare with ftpd that uses sendfile() kernel function.
  system  ftpd  twice  slower  (or  I can not find good FTP client for
  Windowsn  -- I've tried FAR, wget/cygwin and "native" ftp), but load
  is significally less.

  On  the  other  hand,  when I rebuilt kernelk wit DEVICE_POLLING and
  turned  polling  on,  load decrease to 10-15% of one core in case of
  samba :)

-- 
// Black Lion AKA Lev Serebryakov <lev at serebryakov.spb.ru>