From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E0B51E86F for ; Tue, 30 Jul 2024 13:30:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722346229; cv=none; b=pCfLTfGMlEI7hBbsdiaDIbCBYXkFL0M3+TFrUCL4gr0BBuHurgh9SuBIeTBF6PwDtkBrsNjGCdxj9muXWPmKmLVu0i/NVJYIY2BwzL4K3EuHBDVCGXbU/8vJwJh2iiLXyMwI0joq7P1ym5HkIB6mEwD2tVnHASxHu7Y3YZy5iZ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722346229; c=relaxed/simple; bh=gVicrh3jvYLnTMxXhgMab0yBqgqb1GZVpcr3RF8zNmE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bDg1keTwJxb/WhH4yEJivVFo1mShQAVMIfFNdLe9Av3vH3tDJyjPywzy5kfMsPYIetZFknVI2V4bCSxqcPazrn5G+ysJDSSqQhzM17A7Aezd54lx1uI2lgeaeAu31GqFvfNCe5UPN5L9tfX8LWsVGP5NTLswbW8UCCuAzXhTlVg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qfpNHrFm; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qfpNHrFm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73829C32782; Tue, 30 Jul 2024 13:30:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722346229; bh=gVicrh3jvYLnTMxXhgMab0yBqgqb1GZVpcr3RF8zNmE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qfpNHrFmSwoijbxAsAiXMVVwOrH3xjozuYpjaB8VVARTQWRBy2tCHUWg/Vh/qSB/0 ThTlK+addcZpaHhPkRTkC6yI2DLGaYiksj7xaz1UuyJnuODl7WqoKm874o6I3yBcuG KMbXy0/hzgIac4Rx2Q9LxSUnFR/Wye1qPRSEjfwLCrFyw7z7w8yqYvcMqA4MVTttua 3AJM0DHQcL6cBOupUuchkkwceqtUlRkGU7IR4AzJCLt4kwNwJH1WVsVKBXX1kNpEWY Tx7A46cJK4kg1xbVgDoZ/Far7yr24cuRRIF9tldsRFxluHjDwdbaaWp8WEvT9QI5Du RkqBKTlhd3Lpw== Date: Tue, 30 Jul 2024 16:30:23 +0300 From: Leon Romanovsky To: Andrew Sheinberg Cc: linux-rdma@vger.kernel.org Subject: Re: Seeking Guidance: Creating an IBV Multicast Group? Message-ID: <20240730133023.GC4209@unreal> References: <1FF42574-65B2-493A-A779-D27F853063A7@princeton.edu> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1FF42574-65B2-493A-A779-D27F853063A7@princeton.edu> On Mon, Jul 29, 2024 at 01:10:29PM -0400, Andrew Sheinberg wrote: > Hello all, > > I’m not sure if this the right place to ask, but I will give it a try. > > I have a system with many initialized UD queue pairs (info for address handle creations and qp numbers exchanged out-of-band). I am only using libibverbs for establishment (purposefully not using librdmacm, to allow for more flexible environment configuration) — everything is working smoothly for unicast. Now I would like to create a multicast group and attach some of these queue pairs (ibv_mcast_attach); however I am struggling to find any details on how to create such a group (and obtain a proper MGID and MLID). First call to ibv_attach_mcast() will create a new multicast group. > > I found a few examples online but am left with questions: > - There is code within perftest's "multicast_resources.c", but this seems a bit hacky and oddly verbose > - There is code within Nvidia Docs’ "Programming Examples using IBV” showcasing joining an already created multicast group at a given IP address using rdma_cm, but It is unclear how to create the group in the first place > > > Questions (please correct me if these do not make sense): > > 1. What is the role of the OpenSM — is there a C API? SM stands for subnet management and its goal to oversee fabric topology and manage path routing among the nodes. Thanks