Re: Network speed mysteries
On Tue, Oct 26, 2004 at 11:46:02PM +0400, Andrew P. wrote: Just an hour ago I decided to rebuild the file-server kernel - and it takes time to build it there, as it's an old Celeron box with little RAM. By coincidence, some files were being uploaded just when I entered make buildkernel I looked at FileZilla windows, expecting to see the speed drop - but WOW! - the speed was at 7Mbytes/s!!! It then hovered around 6.5-9Mbytes/s while the kernel was being built! I waited for some minutes until the kernel was finally built - and the upload speed dropped back to 2.5-3.5Mb/s. I couldn't believe it - and I still can't - so I waited and built a kernel once more - with all the same effects on speed! It's worth to mention, that when I was installing the built kernel, the speed didn't change from usual 3Mb/s. Please let me know what the heck is going on - or just what you think about it. So, when the system is under load, the network throughput goes up? That must be a timing issue to do with dealing with ACKs -- perhaps the FreeBSD box just responds too fast for the other end, and loading down the system delays things just long enough to get both ends into sync. What would be useful would be to use tcpdump(1) or ethereal(1) to capture a sample of the network traffic in either situation and bring this up on the [EMAIL PROTECTED] list. Note that running tcpdump itself might affect the traffic in a similar way -- there's a thread on freebsd-net which you might find interesting, starting here: http://lists.freebsd.org/pipermail/freebsd-net/2004-October/005368.html I you do post to freebsd-net, including the output of 'ifconfig -a' would be a good move. Cheers, Matthew -- Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way PGP: http://www.infracaninophile.co.uk/pgpkey Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK pgppkTwq4MRse.pgp Description: PGP signature
Re: Network speed mysteries
Matthew Seaman wrote: On Tue, Oct 26, 2004 at 11:46:02PM +0400, Andrew P. wrote: Just an hour ago I decided to rebuild the file-server kernel - and it takes time to build it there, as it's an old Celeron box with little RAM. By coincidence, some files were being uploaded just when I entered make buildkernel I looked at FileZilla windows, expecting to see the speed drop - but WOW! - the speed was at 7Mbytes/s!!! It then hovered around 6.5-9Mbytes/s while the kernel was being built! I waited for some minutes until the kernel was finally built - and the upload speed dropped back to 2.5-3.5Mb/s. I couldn't believe it - and I still can't - so I waited and built a kernel once more - with all the same effects on speed! It's worth to mention, that when I was installing the built kernel, the speed didn't change from usual 3Mb/s. Please let me know what the heck is going on - or just what you think about it. So, when the system is under load, the network throughput goes up? That must be a timing issue to do with dealing with ACKs -- perhaps the FreeBSD box just responds too fast for the other end, and loading down the system delays things just long enough to get both ends into sync. What would be useful would be to use tcpdump(1) or ethereal(1) to capture a sample of the network traffic in either situation and bring this up on the [EMAIL PROTECTED] list. Note that running tcpdump itself might affect the traffic in a similar way -- there's a thread on freebsd-net which you might find interesting, starting here: http://lists.freebsd.org/pipermail/freebsd-net/2004-October/005368.html I you do post to freebsd-net, including the output of 'ifconfig -a' would be a good move. Thanks a lot! When I rebooted after installing my custom kernel, I was delighted to find out that the speed grew to 9.7Mb/s. That's another mystery, cuz I've switched from GENERIC kernel to one with ipfw, ipdivert and some other networking code. So I think I'll just leave it at that. Besides, I don't want to spoil my first impression. I just want to keep wondering - how building a kernel itself can speed up network thruoghput. Real magic :-) Thanks again! Best regards, Andrew P. ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Network speed mysteries
Dear friends I have just stumbled upon a phenomena, which I cannot believe is real, though I reproduced it easily. Some days ago I have set up a FreeBSD-4.10 file-server. I have a small network in my room (3 boxes, 100Mbps). I uploaded some files from my Windows 2000 PC, using the latest version of FileZilla client. The speed was pretty constant at 9.5Mbytes/s. Two days ago I switched to Windows XP SP2, reinstalled all the software and was taken aback when I tried to upload some more files and the speed never exceeded 3.5Mb/s. I browsed and googled for some hours, made dozens of assumptions, tried to reconfigure both Windows and FreeBSD - but it was all in vain. Just an hour ago I decided to rebuild the file-server kernel - and it takes time to build it there, as it's an old Celeron box with little RAM. By coincidence, some files were being uploaded just when I entered make buildkernel I looked at FileZilla windows, expecting to see the speed drop - but WOW! - the speed was at 7Mbytes/s!!! It then hovered around 6.5-9Mbytes/s while the kernel was being built! I waited for some minutes until the kernel was finally built - and the upload speed dropped back to 2.5-3.5Mb/s. I couldn't believe it - and I still can't - so I waited and built a kernel once more - with all the same effects on speed! It's worth to mention, that when I was installing the built kernel, the speed didn't change from usual 3Mb/s. Please let me know what the heck is going on - or just what you think about it. Best regards, Andrew P. ___ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
