From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH V1 rdma-core 1/3] verbs: Enable creating QP with a given source QP number Date: Mon, 11 Sep 2017 10:28:54 -0600 Message-ID: <20170911162854.GE32117@obsidianresearch.com> References: <1504786327-820-1-git-send-email-yishaih@mellanox.com> <1504786327-820-2-git-send-email-yishaih@mellanox.com> <20170907151641.GC20644@obsidianresearch.com> <20170907192909.GA5364@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alex Rosenbaum Cc: Yishai Hadas , linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Majd Dibbiny List-Id: linux-rdma@vger.kernel.org On Sun, Sep 10, 2017 at 09:54:45AM +0300, Alex Rosenbaum wrote: > On Thu, Sep 7, 2017 at 10:29 PM, Jason Gunthorpe > wrote: > > On Thu, Sep 07, 2017 at 09:46:39PM +0300, Alex Rosenbaum wrote: > >> On Thu, Sep 7, 2017 at 6:16 PM, Jason Gunthorpe > >> wrote: > >> > On Thu, Sep 07, 2017 at 03:12:05PM +0300, Yishai Hadas wrote: > >> >> +uint32_t source_qpn; /* Source QP number, creation flag IBV_QP_CREATE_SOURCE_QPN should be set */ > >> > > >> > I think more discussion in the man page is required for this > >> > feature. Eg that it is a SEND ONLY QP and only works for UD. > >> > >> Verbs UD QP can handle receive of ingress packets sent with > >> BTH.DestQPN = ibv_qp->qp_num. This is applicable also in this case. > >> > >> Also, future implementation might include RC source qpn use case. This > >> can be accomplished by setting the HCA's QPN to be the same as the > >> 'source qpn' value, and returning that to the user. > >> > >> We prefer not to limit the API definition in the man page. > > > > Well, you have to define what the API does, specifically. > > > > If you expect it to RX then you need to specify that. > > Like any other QP, this too can have a max_recv_wr defined by user. I > don't think we need to specifically mention it, because it is not a > limition. You need to mention what impact source_qpn has on the RX, assuming the user does nothing else. >>From what I can gather, without flow steering, RX should not be possible. This needs to be described. > > There is nothing wrong with specifying the API limit that exist today, > > it helps people understand what the feature is and how to use it. > > RC is currently not supported. Do you prefer we update the man page > with the UD limitation? and once RC or other limitation are removed we > update it again? Yes. Describe what it does. The man page is not a spec, it documents what the software actually does. Jason -- 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