From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset=us-ascii; format=flowed; delsp=yes Mime-Version: 1.0 (Apple Message framework v1076) From: Eric Van Hensbergen In-Reply-To: Date: Wed, 14 Oct 2009 20:17:02 -0600 Content-Transfer-Encoding: 7bit Message-Id: References: To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Subject: Re: [9fans] Barrelfish Topicbox-Message-UUID: 86df26ae-ead5-11e9-9d60-3106f5b1d025 On Oct 14, 2009, at 8:05 PM, Roman Shaposhnik wrote: >> And how does one deal with heterogeneous cores and complex on chip >> interconnect topologies? > > Good question. Do they have to be heterogeneous? My oppinion is that > the > future of big multicore will be more Cell-like. > They don't have to be, but that is part of both the multikernel and satellite kernel vision. >> There's no real evdence that single kernels do well with hundreds >> of real >> cores (as opposed to hw threads) - in fact most of the data I've >> seen is to >> the contrary. > > Agreed. But then, again, you don't really want a kernel for anything > but message > passing in such an architecture (the other function of the kernel -- > multiplexing > I/O is only needed on selected few cores) at which point it really > becomes a > misnomer to even call it a kernel -- a thin hypervisor perhaps... > If you look at the core of Barrelfish, you'll see that this is essentially what they are doing -- essentially using an extremely small microkernel (like L4) that's very efficient at various forms of message passing. That's the only thing that is duplicated on the various cores. The services themselves can be distributed and/or replicated as appropriate (although their approach favors replication) -- it all depends on the characteristics of the workload. -eric