Re: Receive offloads, small RCVBUF and zero TCP window

2016-11-30 Thread Alex Sidorenko
On Monday, November 28, 2016 4:14:04 PM EST Alex Sidorenko wrote: > On Monday, November 28, 2016 3:54:59 PM EST David Miller wrote: > > From: Alex Sidorenko > > Date: Mon, 28 Nov 2016 15:49:26 -0500 > > > > > Now the question is whether is is OK to have icsk->icsk_ack.rcv_mss > > > larger than MT

Re: Receive offloads, small RCVBUF and zero TCP window

2016-11-28 Thread Marcelo Ricardo Leitner
On Mon, Nov 28, 2016 at 03:54:59PM -0500, David Miller wrote: > From: Alex Sidorenko > Date: Mon, 28 Nov 2016 15:49:26 -0500 > > > Now the question is whether is is OK to have icsk->icsk_ack.rcv_mss > > larger than MTU. > > It absolutely is not OK. > Would it make sense to add a pr_warn_once()

Re: Receive offloads, small RCVBUF and zero TCP window

2016-11-28 Thread Alex Sidorenko
On Monday, November 28, 2016 3:54:59 PM EST David Miller wrote: > From: Alex Sidorenko > Date: Mon, 28 Nov 2016 15:49:26 -0500 > > > Now the question is whether is is OK to have icsk->icsk_ack.rcv_mss > > larger than MTU. > > It absolutely is not OK. > > If VMWare wants to receive large frames

Re: Receive offloads, small RCVBUF and zero TCP window

2016-11-28 Thread David Miller
From: Alex Sidorenko Date: Mon, 28 Nov 2016 15:49:26 -0500 > Now the question is whether is is OK to have icsk->icsk_ack.rcv_mss > larger than MTU. It absolutely is not OK. If VMWare wants to receive large frames for batching purposes it must use GRO or similar to achieve that, not just send va

Receive offloads, small RCVBUF and zero TCP window

2016-11-28 Thread Alex Sidorenko
One of our customers has met a problem: TCP window closes and stays closed forever even though receive buffer is empty. This problem has been reported for RHEL6.8 and I think that the issue is in __tcp_select_window() subroutine. Comparing sources of RHEL6.8 kernel and the latest upstream kernel