From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: [PATCH V4 for-next 1/5] IB/core: Add RSS and TSS QP groups - suggesting BOF during OFA conf to further discuss that Date: Tue, 30 Apr 2013 10:28:41 -0600 Message-ID: <20130430162841.GA29903@obsidianresearch.com> References: <1828884A29C6694DAF28B7E6B8A823736FD1E64F@ORSMSX109.amr.corp.intel.com> <20130425201255.GB31863@obsidianresearch.com> <1828884A29C6694DAF28B7E6B8A823736FD1EF16@ORSMSX109.amr.corp.intel.com> <20130425204357.GD31863@obsidianresearch.com> <20130425214058.GF31863@obsidianresearch.com> <20130429203653.GA25804@obsidianresearch.com> <517F8919.8060108@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <517F8919.8060108-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Shlomo Pongratz Cc: Or Gerlitz , "Hefty, Sean" , Tzahi Oved , Roland Dreier , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Christoph Lameter List-Id: linux-rdma@vger.kernel.org On Tue, Apr 30, 2013 at 12:04:25PM +0300, Shlomo Pongratz wrote: > >And.. 'tss_qpn_mask_sz' seems unnecessarily limiting, using > > WC.srcQPN + ipoib_header.tss_qpn_offset == real QPN > > (ie use a signed offset, not a mask) > >Seems much better than > > Wc.srcQPN & ~((1<<(ipoib_header.tss_qpn_mask_sz >> 12))-1) == real QPN > > (Did I even get that right?) > Your suggestion could have been valid if the the IPoIB header was larger. > Please note that the a QPN occupies 3 octets and thus its value lies > in the range of [0..0xFFFFFF]. I am aware of this, and it isn't really a problem, adaptors that allocate randomly across the entire QPN space would not be compatible with this approach, but most adaptors allocate QPNs quasi-contiguously. Basically, at startup, IPoIB would allocate a TX QP, then allocate TSS QPs, and throw away any that can't fit in the encoding, until it reaches the target number or tries too long. No need for a special API to the driver. 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