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.
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