Hello there, I think I found a performance issue in the kernel (2.6.32/amd64) of the squeeze release.
I tested from different servers and each time made a wget of a 16 MB file from a remote co-location which is connected with gigabit (but the issue showed also on a 32MBit/s "dial-up" cable connection). The squeeze system starts the transfer significantly slower and takes longer to get faster over time (on a 2GB file the maximum was reached after 12 seconds). The lenny system reaches this maxium very fast so the overall time drops from 2.4s to 0.4s. It could be, this is related to changes in TCP/IP behaviour. I could not see this behaviour in the same subnet, it shows up, as soon as routing is involved in the connection. I made two graphs with tcpdump and wireshark from the remote host during the wget from the servers which stand side by side in the rack on the same switch. You can see them under http://www.youimage.com/a/TPaszvOgtrM$/ On a lenny system with 2.6.26 everything works fine. All our the new servers with squeeze (and the 2.6.32) show the issue. If I substitute the standard kernel from squeeze with the current backports 2.6.39-bpo.2 kernel everthing is working again. So I strongly believe the issue is related to the kernel. I diffed a "sysctl -a" from the lenny system and the not properly working squeeze systems with nearly no differences at all, but set all the values as they were on the lenny system - just to be sure with no luck. If I can help any further please let me know, I will try as good as I can. If someone can confirm this, I am of course able to file a bugreport. regards Thorsten -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/4e5e0d62.7090...@anw.de
