Re: [uCsimm] cat and telnet performance problems

From: Donald J Dionne (jdionne@ns1.rt-control.com)
Date: Thu Jan 06 2000 - 13:58:04 EST


>
> Looks like this is a common problem with TCP socket code. I have some
> other programs that write directly into a TCP socket and experience the
> same kind of "bursted" output regardless of whether Ethernet or PPP is
> used. Since telnetd is not involved there, all PTY code and telnetd
> are not suspected anymore.
>
> I did a quick look, but could not find any uClinux-specific stuff in the
> socket code.

There is no uClinux specific socket (or tcp for that matter) code. We did
have to fix the PPP layer some, it had alignment problems. The ethernet
layer has no changes. There are changes in the proc filesystem to deal
with writeable strings, but that's not what's going on.

Something in the back of my head says look at the "nagle" code and see if
it is interacting with the jiffie clock in some unexpected way. Although
there are no uClinux changes to the jiffie clock (with the exception of
making sure it's hooked up to the periodic interrupt). I'm thinking
something hard coded where there sould be the macro HZ insted (ok, that's
a long shot).

>
> Any ideas what might be broken?

Try opening the socket with the option for disable nagle.

Jeff.

>
> Regards,
> Vladimir
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