From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH for-next V2 0/9] Add completion timestamping support Date: Thu, 4 Jun 2015 10:47:59 -0600 Message-ID: <20150604164759.GC27699@obsidianresearch.com> References: <1433074457-26437-1-git-send-email-ogerlitz@mellanox.com> <1433098827.114391.179.camel@redhat.com> <1433157904.114391.188.camel@redhat.com> <20150601164322.GA14391@obsidianresearch.com> <1433255724.114391.225.camel@redhat.com> <20150602180844.GD17776@obsidianresearch.com> <1828884A29C6694DAF28B7E6B8A82373A8FE4F16@ORSMSX109.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1828884A29C6694DAF28B7E6B8A82373A8FE4F16-P5GAC/sN6hkd3b2yrw5b5LfspsVTdybXVpNB7YpNyf8@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Hefty, Sean" Cc: Doug Ledford , Matan Barak , Or Gerlitz , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Amir Vadai , Tal Alon List-Id: linux-rdma@vger.kernel.org On Thu, Jun 04, 2015 at 04:17:35PM +0000, Hefty, Sean wrote: > > No, if they followed (I didn't check yes) the extension scheme then the > > poll call is > > > > struct ibv_wc_ex wcs[num_wcs] > > ibv_poll_wc_ex(&wcs,num_wcs,sizeof(wcs[0])); > > > > And the drivers decide what to do based on the 3rd argument, which is > > essentially the ABI version. > > As a couple of options: > > You could add a 'completion format' field to the cq attribute > structure, which would allow poll to cast to a specific structure. Subtle, and tricky to use.. But sure.. > If we wanted to go with Doug's earlier idea, you could add a > 'provider context' field to the wc. This would allow calling back > into the provider to retrieve more data. Though, this concept would > be racy if other completions can overwrite whatever data was trying > to be retrieved. Right, in the model we have where poll advances the HW completion queue, that is not straightforward at all. Can you share what the libfabric change would look like to add a timestamp field to the completion? That might be informative, libfabric is also consuming the kernel UAPI. 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