Re: slow writes on nfs with bge devices

On Sun, 21 Jan 2007, Max Laier wrote:

On Sunday 21 January 2007 13:25, Bruce Evans wrote:
On Sun, 21 Jan 2007, Max Laier wrote:
On Sunday 21 January 2007 07:25, Bruce Evans wrote:
nfs writes much less well with bge NICs than with other NICs (sk,
fxp,

Do you use hardware checksumming on the bge? There is an XXX in
bge_start_locked() that looks a bit suspicious to me.

I use the default for that. Wouldn't checksum problems show up as
errors somwhere?

Did you look at the code in question? It is concerned with fragmented
packet chains (which NFS over UDP usually generated) and only commits to
sending them, if there are enough descriptors available at once. This
can easily explain burstyness.

Can you just try to disable the delayed checksums via "ifconfig -txcsum"?
Should be an easy enough test.


I realize that Bruce has already identified the problem as being with
the cabling, however I wanted to add a warning that disabling hardware
checksums for bge cards is not a good idea. You can find my analysis of
data corruption bugs caused by using bge cards without checksum
offloading in the archives:
http://lists.freebsd.org/pipermail/freebsd-net/2004-January/002530.html

Kelly

--
Kelly Yancey - kbyanc@xxxxxxxx | kelly@xxxxxxxxxx
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