Messages in this thread | | | Date | Mon, 19 Jul 2004 20:13:04 +0200 | From | Maciej Soltysiak <> | Subject | [partially solved] tcp_window_scaling degrades performance |
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> AK> It is very very likely the firewall, window scaling works for a lot > AK> of people. > It is probable, but here: only 2.6.7+ machines behave like this. > I also noticed, that turning tcp_window_scaling off does not always > fix the problem, turning tcp_bic to 0 too helps even more. It appears that checkpoint fw-1 that is here spoils everything so that current linux boxes need to disable tcp_windows_scaling to get reasonable throughput. When I switched a server to a different link that bypasses checkpoint it worked well.
Although it most propably is checkpoint's fault (This one is based on linux 2.4.9-39cpsmp) I belive that the change in the kernel that started producing these problems is this one: http://linux.bkbits.net:8080/linux-2.6/cset@1.1784.10.7?nav=index.html|ChangeSet@-3w
When I removed this patch from a 2.6.8-rc1 kernel it started to work good again. But of course it may be a blind shot.
I am planning on investigating this issue from the checkpoint's perspective.
Anyway if there is anyone willing to investigate the tcpdumps and tcptraces of the slow/fast throughput, here it is: http://soltysiak.com/tcp.php
I am no guru, but it shows: 1) slower throughput 2) twice as much packets exchanged 3) different advertised windows
Best regards, Maciek
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