I have a Red Hat Enterprise Linux 6 (with SELinux) which shows significant differences of speed between download and upload (the latter significantly slower) of files shared over the LAN.
The bottleneck seems to be the output of the linux machine since I have a rate around 1Mb/s
- when WinXP machines download files shared (using samba) by the RHEL machine
- uploading files from the RHEL to a WinXP's shared folder
- uploading from the XP machines to linux's shares
- downloading XPs' shares on the RHEL
- any share between Windows machines only
run smooth (around 50Mb/s).
Since the upload from RHEL to WinXP's share is slowed too I would exclude an issue in the configuration of samba.
What could possibly determine this limit in the upload speed?
update: iptables doesn't show any output rule and disabling it doesn't show any noticeable difference, so I would rule out it too.