From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: <13426df10910171706o6f6b9274w34b6d262d68ca387@mail.gmail.com> References: <4030fb6ae37f8ca8ae9c43ceefbdf57b@ladd.quanstro.net> <13426df10910171706o6f6b9274w34b6d262d68ca387@mail.gmail.com> Date: Sun, 18 Oct 2009 00:54:48 +0000 Message-ID: From: Roman Shaposhnik To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Content-Type: text/plain; charset=ISO-8859-1 Subject: Re: [9fans] Barrelfish Topicbox-Message-UUID: 89938476-ead5-11e9-9d60-3106f5b1d025 On Sun, Oct 18, 2009 at 12:06 AM, ron minnich wrote: > the use of qualitative terms such as "embarassingly parallel" often > leads to confusion. > > Scaling can be measured. It can be quantified. Nothing scales forever, > because at some point you want to get an answer back to a person, > and/or the components of the app need to talk to each other. It's > these basic timing elements that can tell you a lot about scaling. > Actually running the app tells you a bit more, of course. > > Even the really easy apps hit a wall sooner or later. I still remember > the struggle I had to scale a simple app to a 16 node cluster in the > early days (1992). That was a long time ago and we've gone a lot > further than that, but you'd be surprised just how hard it can be, > even with "easy" applications. Can't agree more. I'd say the biggest problem I have with "embarassingly parallel" is the fact that it conjures up images of linear increase of speedup. Nobody ever does math or even experiments to see how quickly we reach point of diminishing returns. Thanks, Roman.