From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: Ummunotify: progress at last! Date: Wed, 7 Apr 2010 14:05:14 -0600 Message-ID: <20100407200514.GI15629@obsidianresearch.com> References: <1CDB2AA4-A8DF-4169-943E-4EA190814596@cisco.com> <20100323165920.GH29129@obsidianresearch.com> <20100323172953.GI29129@obsidianresearch.com> <5F80899D-F989-4162-B050-7E4D6B389876@cisco.com> <20100323195251.GJ29129@obsidianresearch.com> <3B848E1F-C9B6-416A-9E6E-99604E71902A@cisco.com> <20100323201124.GK29129@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: Roland Dreier Cc: Jeff Squyres , Linux RDMA List , Brad Benton List-Id: linux-rdma@vger.kernel.org On Wed, Apr 07, 2010 at 12:37:03PM -0700, Roland Dreier wrote: > > No, there is no mmap. Like this: > > > > u64 my_counter = 0; > > > > ibv_set_mmu_counter(verbs, &my_counter); > > [..] > > while (my_counter != last_my_counter) { > > last_my_counter = my_counter; > > ibv_get_mmu_notifications(verbs, ...); // <- I am a memory barrier as well > > } > > > > The kernel 'syscall' ibv_set_mmu_counter would bind the given verbs to > > the 8 byte counter you specified without having to the mmap thing. As > > I understand it this is what perfevents does. > > I was trying to look at how perf events handles this, and AFAICT it > looks like kernel/perf_event.c just supports mmap(). Can you expand on > what you meant here? > > (I was trying to figure out how one would handle the case where > userspace gives us a counter in highmem -- doing kmap_atomic() seems to > be to only option but then I'm not sure if I want to deal with that...) I think I was mistaken here, disregard.. 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