Andy - I spoke too soon; there were evidently just a few giants left
in the queue when I did the change. After an hour, all giants
ceased. Thanks again - it works much better now.
Stone
On Aug 1, 2007, at 4:26 PM, Andy Furniss wrote:
Stonie Cooper wrote:
Andy - Thanks!
I took the ethtool path, and turned off tcp segmentation on that
nic; I was unsure how to set the HTB MTU - I use shorewall on a
Gentoo system.
I think you would need to find each line with a rate in the script
and add mtu X - I don't know what X would be, though.
It has definitely made a difference. The highest rate I see is
282312bits on a line with a ceil of 282000bits - and that is with
24pps, which, according to your previous email . . . would be
right in line with what it should be.
If you are shaping for a wan then I would turn off tso rather than
use mtu. It should be better for latency as a big chunk of data is
going to take more time to be transmitted and hurt interactive
traffic. I can't imagine it being very good to effectively drop
multiple segments at once either - but then shorewall may not setup
with queues short enough to get drops.
Giants have fallen off, but are not completely eliminated. Is
this something I should be concerned with (having giants)?
As long as there aren't many I wouldn't care - I don't know why you
still see them, though. I haven't got any nics that do tso so can't
test.
Would setting the
HTB MTU be more elegant? I have avoided creating my own tc
script, and have been using shorewall's internals . . . but if
utilizing the HTB MTU setting is "better", I will dive in and try
to write a script that does the same thing as shorewall.
You would also loose some accuracy in the rate lookup tables if you
used mtu 16,32,64 etc. bytes depending on how big an mtu you needed
to use.
If you have a slow dsl link and really care about latency or not
having to back off from it's rate, then there are other ways to
tweak things. They involve patching and recompiling kernel/tc.
Andy.
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