From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ira Weiny Subject: Re: [infiniband-diags] [libibmad] Support new ibccquery congestion control tool Date: Wed, 21 Sep 2011 11:09:48 -0700 Message-ID: <20110921110948.6f3d46ff.weiny2@llnl.gov> References: <1316469989.25283.728.camel@auk59.llnl.gov> <20110921084934.b300e682.weiny2@llnl.gov> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110921084934.b300e682.weiny2-i2BcT+NCU+M@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ira Weiny Cc: Hal Rosenstock , "Chu, Al" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On Wed, 21 Sep 2011 08:49:34 -0700 Ira Weiny wrote: > On Wed, 21 Sep 2011 07:17:38 -0700 > Hal Rosenstock wrote: > > > Hi Al, > > > > > On 0001-Support-ibccquery-congestion-control-query-tool.patch, I'm > > worried about the following: > > + /* XXX: Q3/2010 errata lists first entry offset at 80, but we assume > > + * will be updated to 96 once CurrentTimeStamp field is word aligned. > > + * In addition, assume max 13 log events instead of 16. Due to > > + * errata changes increasing size of CA log event, 16 log events is > > + * no longer possible to fit in max MAD size. > > + */ > > > > As far as the 13 v. 16 entries, this appears correct to me (MAD size) > > but I'm concerned about changing the offset from 80 to 96 for better > > alignment as this is putting the cart before the horse a little as > > since these changes have not been finalized AFAIK at the IBTA. > > Yes, it is a bit premature. I have submitted the above alignment as a comment > to the IBTA but as you say it is not published. Most importantly the > miss-alignment breaks the convention of the spec. So I don't think the IBTA > will reject the comment. > > Second the current alignment breaks libibmad. So it would be a lot more code > to support the miss-alignment and would probably have to be changed anyway. > > > > > Also, would you comment on what testing has been done with this ? > > > > Right, the real question is what does current hardware do? > > We have been unable to determine if any of the vendors support the errata > fully or specifically the miss-aligned CurrentTimeStamp. When I asked the > vendors I got concrete answers back, so we proceeded with trying to reverse ^^^ I meant to say "no concrete" answers here. Sorry, Ira > engineer it. Right now the query succeeds, that is all we know. > > Perhaps someone on the list can help us find out? :-D > > In the meantime we wanted to get comments on the patches. > > Ira > > > -- Hal > > > > > Al > > > > > > -- > > > Albert Chu > > > chu11-i2BcT+NCU+M@public.gmane.org > > > Computer Scientist > > > High Performance Systems Division > > > Lawrence Livermore National Laboratory > > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > > the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- > Ira Weiny > Member of Technical Staff > Lawrence Livermore National Lab > 925-423-8008 > weiny2-i2BcT+NCU+M@public.gmane.org -- Ira Weiny Member of Technical Staff Lawrence Livermore National Lab 925-423-8008 weiny2-i2BcT+NCU+M@public.gmane.org -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html