From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965183AbeE2QQq (ORCPT ); Tue, 29 May 2018 12:16:46 -0400 Received: from aserp2130.oracle.com ([141.146.126.79]:58562 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964848AbeE2QQo (ORCPT ); Tue, 29 May 2018 12:16:44 -0400 Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.3 \(3445.6.18\)) Subject: Re: [PATCH] IB/mad: Use ID allocator routines to allocate agent number From: =?utf-8?Q?H=C3=A5kon_Bugge?= In-Reply-To: <20180529154922.GA18457@ziepe.ca> Date: Tue, 29 May 2018 18:16:14 +0200 Cc: Hans Westgaard Ry , Doug Ledford , Jack Morgenstein , Daniel Jurgens , Parav Pandit , Pravin Shedge , OFED mailing list , linux-kernel@vger.kernel.org Message-Id: References: <20180529073808.27735-1-hans.westgaard.ry@oracle.com> <20180529154922.GA18457@ziepe.ca> To: Jason Gunthorpe X-Mailer: Apple Mail (2.3445.6.18) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8908 signatures=668702 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=15 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=906 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1805290179 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w4TGGqur005069 > On 29 May 2018, at 17:49, Jason Gunthorpe wrote: > > On Tue, May 29, 2018 at 09:38:08AM +0200, Hans Westgaard Ry wrote: >> The agent TID is a 64 bit value split in two dwords. The least >> significant dword is the TID running counter. The most significant >> dword is the agent number. In the CX-3 shared port model, the mlx4 >> driver uses the most significant byte of the agent number to store the >> slave number, making agent numbers greater and equal to 2^24 (3 bytes) >> unusable. > > There is no reason for this to be an ida, just do something like > > mad_agent_priv->agent.hi_tid = atomic_inc_return(&ib_mad_client_id) & mad_agent_priv->ib_dev->tid_mask; > > And have the driver set tid_mask to 3 bytes of 0xFF The issue is that some of the mad agents are long-lived, so you will wrap and use the same TID twice. Thxs, Håkon > > And no sysctl. > > Jason > -- > To unsubscribe from this list: send the line "unsubscribe linux-rdma" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html