I tested again on Linux 2.6.25 with TCP reordering patch.Of course, TCP performance was improved.
Here is the result.
 case2-2) random delay (with TCP reordering patch)
  In this case, add a fixed amount of delay + 10% random delay by command,  "tc change dev eth0 root netem delay 100ms 10ms 25%".
    fixed delay    UDP/TCP/XTP throghput  ---------------------------------------      10ms         88/85/92 Mbps      30ms         88/67/91 Mbps      50ms         88/58/89 Mbps      70ms         88/43/80 Mbps     100ms         88/26/66 Mbps
 case2) random delay (without TCP reordering patch)
  In this case, add a fixed amount of delay + 10% random delay by command,  "tc change dev eth0 root netem delay 100ms 10ms 25%".
    fixed delay    UDP/TCP/XTP throghput  ---------------------------------------      10ms         88/80/92 Mbps      30ms         88/51/91 Mbps      50ms         88/41/89 Mbps      70ms         88/28/80 Mbps     100ms         88/19/66 Mbps
  case1) fixed delay
    In this case, just adds a fixed amount of delay to all packets going out by  command, "tc qdisc add dev eth0 root netem delay 100ms".
    fixed delay    UDP/TCP/XTP throghput  ---------------------------------------      10ms         88/85/92 Mbps      30ms         88/70/91 Mbps      50ms         88/63/89 Mbps      70ms         88/52/84 Mbps     100ms         88/36/70 Mbps
Thanks,
On Fri, Apr 25, 2008 at 5:23 PM, Ilpo Järvinen<ilpo.jarvinen@helsinki.fi> wrote:> On Fri, 25 Apr 2008, Shigeo N wrote:>>> case2) random delay>>>>  In this case, add a fixed amount of delay + 10% random delay by>> command, "tc change dev eth0 root netem delay 100ms 10ms 25%".>>>>  Here is the result.>>>>     fixed delay    UDP/TCP/XTP throghput>>   --------------------------------------->>       10ms         88/80/92 Mbps>>       30ms         88/51/91 Mbps>>       50ms         88/41/89 Mbps>>       70ms         88/28/80 Mbps>>      100ms         88/19/66 Mbps>>>>  TCP's perfomance looks very poor when delay is long and variable.>> Where these results with 2.6.25 as well? ...John Heffner just couple of> days ago fixed reordering related problem in TCP (in case that netem> parametrization causes reordering), the fix is not even in 2.6.24.y, I> think...>> -->  i.>���{.n�+�������+%�����ݶ��w��{.n�+����{��G�����{ay�ʇڙ�,j��f���h��������z_�(�階�ݢj"���m������G������?����&���~��iO��z��v�^�m����������?�I�