search for: tcpackfrequ

Hello, I've a CentOS-5 system (kernel-2.6.18-8.1.14el5) SMP arch running samba-3.0.27a. A user reported extremely long load time (11 minutes) of a 43MB file across a 3Mb/sec WAN link. Copying the same file to a windows server and opening it from there on the same client system took about 2:30. Research found the below thread from April:

...iour (XP slow, 2K fast) - FTP from the XP machines (runs fast) - rebooting XP - rebooting server - directly connecting XP machine to server - XP copy to Win2k (fast) But with no luck. The time (estimated) to copy a 2 GB file is > 200 minutes. Microsoft KB articles talk about changing TcpAckFrequency Values on the server, for slow comms from XP to a Win2K PDC (http://support.microsoft.com/?kbid=321169) but this is on the server, and the same article talks about changing RequireSecuritySignature & EnableSecuritySignature (on the client, I think), but these are already set to 0. The...

...s Server -> Desktop is abysmally slow (about 0.1% wire speed) - Transferring files Desktop -> Server is sometimes slow (about 1% wire speed), sometimes at normal speed (about 30-40% wire speed). So it can do it ! But only when it wants. So frustrating. With TCP Delayed ACKs disabled (TcpAckFrequency=1) : - Browsing is correct - Transferring files Server -> Desktop is slow (about 5% wire speed) - Transferring files Desktop -> Server : same as above. The laptop has delayed ack's anyway and it's very fast... This is with the Desktop connected through its nvidia onboard g...

...be smth wrong with ACKs sent from WinXP. I've tried to search for problems with ACK delays in WinXP and found the following articles: http://support.microsoft.com/kb/328890 http://support.microsoft.com/kb/321098 Based on them, I've done the following changes in WinXP registry: - set TcpAckFrequency to 1 to switch off delayed ACKs - set TcpDelAckTicks to 0 to disable delayed ACKs timer These changes did not help on their own. But combining them with the change of SO_SNDBUF to 1500 suddenly improved the speeds up to about 6 Mb/s! It appeared that with these registry changes, setting...