From mboxrd@z Thu Jan 1 00:00:00 1970 To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> In-reply-to: Your message of "Sun, 18 Oct 2009 06:22:33 PDT." References: <20091015105328.GA18947@nipl.net> <20091018031508.717CE5B30@mail.bitblocks.com> From: Bakul Shah Date: Sun, 18 Oct 2009 12:18:21 -0700 Message-Id: <20091018191821.BD0ED5B75@mail.bitblocks.com> Subject: Re: [9fans] Barrelfish Topicbox-Message-UUID: 89c22c40-ead5-11e9-9d60-3106f5b1d025 On Sun, 18 Oct 2009 06:22:33 PDT Roman Shaposhnik wrote: > On Sun, Oct 18, 2009 at 6:06 AM, Roman Shaposhnik wrot > e > >> It is. But what's your proposal on code sharing? All those PC > >> registers belonging to > >> different cores have to point somewhere. Is that somewhere is not shared m > e= > >> mory > >> the code has to be put there for every single core, right? > > > > At the hardware level we do have message passing between a > > processor and the memory controller -- this is exactly the > > same as talking to a shared server and has the same issues of > > scaling etc. If you have very few clients, a single shared > > server is indeed a cost effective solution. > > I guess I'm not following. My question to OP was strictly about > code sharing. Basically were do the cores get instructions from > if not from shared memory. Sorry, I should've done a better job of editing. I was really responding to the OP's point that sharing memory between processes is a stupid approach. My point was that "sharing memory" is just a low level programming interface (implemented by message passing in h/w) and it makes sense at some scale.