From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jack Morgenstein Subject: Re: [RFC] XRC upstream merge reboot Date: Thu, 23 Jun 2011 09:35:07 +0300 Message-ID: <201106230935.07425.jackm@dev.mellanox.co.il> References: <1828884A29C6694DAF28B7E6B8A82373F7AB@ORSMSX101.amr.corp.intel.com> <201106222221.05993.jackm@dev.mellanox.co.il> <1828884A29C6694DAF28B7E6B8A82373029BDE@ORSMSX101.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1828884A29C6694DAF28B7E6B8A82373029BDE-P5GAC/sN6hmkrb+BlOpmy7fspsVTdybXVpNB7YpNyf8@public.gmane.org> Content-Disposition: inline Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Hefty, Sean" Cc: "linux-rdma (linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org)" , "tziporet-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org" , "dotanb-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org" List-Id: linux-rdma@vger.kernel.org On Wednesday 22 June 2011 22:57, Hefty, Sean wrote: > > > We can report the creation of a tgt qp on an xrcd as an async eve= nt. > > To whom? >=20 > to all users of the xrcd. =A0IMO, if we require undefined, out of ban= d communication to use > XRC, then we have an incomplete solution. =A0It's just too bad that w= e can't report additional > data (like the tgt qpn) with an async event... =20 >=20 I do not think this will help much. Just knowing that a TGT QP exists = is not really relevant. The sender (who is on a remote host) needs to know about the TGT QP, to use it to send to the XRC SRQs. We c= annot propagate an event over to the sender side! The local users of the TGT QP don't really care -- it is the responsibility of the Appl= ication to get the INI-TGT linkage up, and the XRC SRQs created before sending from INI to SRQ. At that point, the SRQ either receives packet= s or it does not. I do agree, though, that the need to use out-of-band communication (rat= her than the CM) to establish the INI-TGT RC connection is not clean. If you are thinking of using this for tracking, there is no way that I = can see except reference counting to know when all users of the TGT hav= e finished with it. Indicating usage by "tapping" the TGT QP whenever an= SRQ receives a packet via the TGT is not a good idea (this is data path!), not to mention that quiescence is not a good indicator of wheth= er an app is done using the target (the amount of time that things are quiet depends on the app). We discussed using a "heartbeat" in the thread link I sent you, and ult= imately discarded that idea. If you have other ideas which you think might work, please send them al= ong. -Jack -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html