svn commit: r296689 - head/sys/dev/cxgbe

[Navdeep Parhar]

On Sun, Mar 13, 2016 at 04:14:34AM +0300, Slawa Olhovchenkov wrote:
> On Fri, Mar 11, 2016 at 11:24:05PM +0000, Navdeep Parhar wrote:
> 
> > Author: np
> > Date: Fri Mar 11 23:24:04 2016
> > New Revision: 296689
> > URL: https://svnweb.freebsd.org/changeset/base/296689
> > 
> > Log:
> >   cxgbe(4): sysctls to display the TOE's TCP timers.
> >   
> >   cask:~# sysctl -d dev.t5nex.0.toe
> >   dev.t5nex.0.toe.finwait2_timer: FINWAIT2 timer (us)
> >   dev.t5nex.0.toe.initial_srtt: Initial SRTT (us)
> >   dev.t5nex.0.toe.keepalive_intvl: Keepidle interval (us)
> >   dev.t5nex.0.toe.keepalive_idle: Keepidle idle timer (us)
> >   dev.t5nex.0.toe.persist_max: Persist timer max (us)
> >   dev.t5nex.0.toe.persist_min: Persist timer min (us)
> >   dev.t5nex.0.toe.rexmt_max: Retransmit max (us)
> >   dev.t5nex.0.toe.rexmt_min: Retransmit min (us)
> >   dev.t5nex.0.toe.dack_timer: DACK timer (us)
> >   dev.t5nex.0.toe.dack_tick: DACK tick (us)
> >   dev.t5nex.0.toe.timestamp_tick: TCP timestamp tick (us)
> >   dev.t5nex.0.toe.timer_tick: TP timer tick (us)
> >   ...
> >   
> >   cask:~# sysctl dev.t5nex.0.toe
> >   dev.t5nex.0.toe.finwait2_timer: 9765440
> >   dev.t5nex.0.toe.initial_srtt: 244128
> >   dev.t5nex.0.toe.keepalive_intvl: 73240800
> >   dev.t5nex.0.toe.keepalive_idle: 7031116800
> >   dev.t5nex.0.toe.persist_max: 9765440
> >   dev.t5nex.0.toe.persist_min: 976544
> >   dev.t5nex.0.toe.rexmt_max: 9765440
> >   dev.t5nex.0.toe.rexmt_min: 244128
> >   dev.t5nex.0.toe.dack_timer: 19520
> >   dev.t5nex.0.toe.dack_tick: 32.768
> >   dev.t5nex.0.toe.timestamp_tick: 1048.576
> >   dev.t5nex.0.toe.timer_tick: 32.768
> >   ...
> 
> Can you more describe it in man?

There are updates and additions to cxgbe documentation in progress,
including new man pages: t4_tom(4) for the TCP offload module (aka TOE
driver), cxgbei(4) for the iSCSI offload driver, and iw_cxgbe(4) for the
iWARP driver.  I'll get these sysctls documented in t4_tom(4).  But
writing decent documentation is harder than writing code and the effort
is taking longer than I'd anticipated, so please be patient.  

> I am see this timers different from system, is this problem? What
> correlations between?

The kernel's TCP stack is different from the TCP implementation in the
chip's silicon and they happen to use different default timers.  Note
that the driver requires you to explicitly load a module (t4_tom) and
then enable IFCAP_TOE on the interfaces in order to use the hardware TCP
offload.  This opt-in model is by design and makes sure you aren't using
a stack that you didn't explicitly ask for.  Offloaded connections show
up as "toe4/6" instead of "tcp4/6" in the output of netstat/sockstat/etc.
so it's easy to tell which socket is using which stack (and which timers).

Regards,
Navdeep