From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] parallel/distributed computation
Date: Sat, 27 Oct 2007 01:53:36 -0400 [thread overview]
Message-ID: <cf6a5892ca12c55b105ea0a23781d9f5@quanstro.net> (raw)
In-Reply-To: <13426df10710262244o625804ebs78881f5eefc53549@mail.gmail.com>
thanks.
- erik
> BSP is essentially all about "the inner loop". In this loop, you do
> the work, and, at the bottom of the loop, you tell everyone what you
> have done.
>
> So you are either computing or communicating. Which means, on your
> $100M computer, that you are using about $50M of it over time. Which
> is undesirable.
>
> Nowadays, people work fairly hard to ensure that while computation is
> happening, the network is busy moving data.
>
> This problem with BSP is well known, which is why some folks have
> tried to time-share the nodes in the following
> way(www.ccs3.lanl.gov/pal/publications/papers/petrini01:feng.pdf):
> have N jobs (N usually 2). While N-1 jobs are using the network, and
> hence not computing, have 1 job computing. Of course, matching this
> all up is hard, and most compute jobs typically are sized to use all
> of memory, so this approach has not been used much. The nodes on the
> big machines are typically not shared between jobs.
>
> BSP was an interesting idea but is not commonly used any more, at
> least on the systems I know about. Rather, people work hard to overlap
> communication and computation.
>
> ron
> p.s. for more recent work see: www.cs.unm.edu/~fastos/06meeting/sft.pdf
next prev parent reply other threads:[~2007-10-27 5:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-17 14:42 lejatorn
2007-10-17 16:13 ` ron minnich
2007-10-17 16:17 ` Eric Van Hensbergen
2007-10-17 16:29 ` David Leimbach
2007-10-17 16:39 ` ron minnich
2007-10-26 9:46 ` Richard Miller
2007-10-26 11:32 ` roger peppe
2007-10-26 12:40 ` Richard Miller
2007-10-26 12:44 ` anyrhine
2007-10-26 15:01 ` ron minnich
2007-10-26 15:04 ` erik quanstrom
2007-10-27 5:44 ` ron minnich
2007-10-27 5:53 ` erik quanstrom [this message]
2007-10-28 15:21 ` Richard Miller
2007-10-18 8:42 ` Randolph Fritz
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