> Cy Schubert wrote: > [stuff snipped] > >The sysctl is net.inet.tcp.tso. You can also disable tso through ifconfig > >for an interface. > > > For testing this case, I'd recommend using the sysctl. Since the net device > driver is often the culprit, that device driver might not handle the "ifconfig" > correctly either. > > Btw, NFS often causes this because... > - Typically TSO is limited to a 64K packet (including TCP/IP and MAC headers). > - When NFS does reading/writing, it will do 64K + NFS, TCP/IP and MAC headers > for an RPC (or a multiple of 64K like 128K). > --> This results in tcp_output() generating a 64K TSO segment followed by a > small TCP segment (since another RPC message doesn;t usually end up > queued quickly enough to fill in the rest of the second TCP segment). > - Also, at the end of file, you can get an RPC which is just under 64K including > NFS and TCP/IP headers. (The drivers often broke when adding the MAC > header bumped this case to > 64K.) > > Thanks go to Yuri for diagnosing this, rick Just a thought, not asking anyone to write one :-) It would be handy to have some sh(1) scripts that can exercise this bug case and have it readily avaliable to network driver authors for testing the tso (or other large segment) code. -- Rod Grimes rgrimes_at_freebsd.orgReceived on Tue Oct 31 2017 - 15:46:59 UTC
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