On Tue, Oct 13, 2009 at 3:44 PM, Ira Weiny <[email protected]> wrote: > On Tue, 13 Oct 2009 09:39:08 -0400 > Hal Rosenstock <[email protected]> wrote: > >> On Mon, Oct 12, 2009 at 5:35 PM, Ira Weiny <[email protected]> wrote: >> > On Mon, 12 Oct 2009 11:47:37 +0200 >> > "Eli Dorfman (Voltaire)" <[email protected]> wrote: >> > >> >> Ira Weiny wrote: >> >> > On Tue, 06 Oct 2009 17:56:01 +0200 >> >> > "Eli Dorfman (Voltaire)" <[email protected]> wrote: >> >> > >> >> >> Hi, >> >> >> >> >> >> Is there a reason for setting default force_link_speed to 15 (set >> >> >> enabled as supported) >> >> >> and not to 0 (don't modify PortInfo:LinkSpeedEnabled )? >> >> This is going back some 2 years to 7/15/07 commit ID >> c7cbf11992b111d2b9c7347e398e67f2b5806edb >> >> commit c7cbf11992b111d2b9c7347e398e67f2b5806edb >> Author: Hal Rosenstock <[email protected]> >> Date: Sun Jul 15 06:43:20 2007 -0400 >> >> OpenSM: Change force_link_speed to allow for local policy and more >> flexibili >> >> OpenSM: Change force_link_speed to allow for local policy and more >> flexibility >> >> Extend (and change) the use of force_link_speed as follows: >> 0 - no change >> 1 - set to SDR >> 15 - set as supported (default) >> (Non zero values are used to set LinkSpeedEnabled component in PortInfo) >> >> Note that force_link_speed 0 which used to force SDR is now >> force_link_speed 1 >> >> "Ideally", there were be a per port configuration of this. > > BTW I have a patch which allows a user to except some nodes from this > restriction. I don't know that anyone but us is using this "feature" so I did > not submit the patch. If someone else would like some finer granularity I can > clean up the patch and make it available.
There are others. This would be a worthwhile improvement IMO. -- Hal > >> >> [Note this is largely untested.] > > BTW, now, this is highly tested, to force SDR, on some of our clusters! > Thanks! > >> >> Signed-off-by: Hal Rosenstock <[email protected]> >> >> I think that the default was chosen based on IBA 1.2.1 vol 2 p. 108 stating: >> "The default value following power on shall be set to LinkSpeedSupported." >> which should not be an issue with compliant hardware. >> > > [snip] > >> > >> > However, I would like to know if anyone else knows of hardware which needs >> > it >> > set to "15". If so, this is going to be an interesting problem... ;-) >> >> I'm not sure about need but I think there is a tradeoff here in >> changing this. The pro is it will work with non compliant hardware. >> The con is that it may result in less than the max LSS being used in >> some scenarios. >> >> Should the default be changed for non compliant hardware or should >> this need to be configured in subnets including such hardware as it >> has since this was introduced ? >> > > I think that is a good way of thinking about things. > > Ira > > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
