2002-07-29 19:01:38 +00:00
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<title>Compute Model: Work Distribution</title>
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<h2>Compute Model: Work Distribution</h2>
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2002-04-30 22:22:54 +00:00
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<p>
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2002-07-29 19:01:38 +00:00
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Results are not necessarily dispatched one at a time. Instead, each
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participant host maintains an estimate of the amount of work remaining
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(i.e. the time until one of its processors will be idle). Each host also
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has two scheduling parameters, the <b>high-water mark</b> and the
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<b>low-water mark</b> (these are part of the host's "preferences",
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discussed later).
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</p>
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2002-04-30 22:22:54 +00:00
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<p>
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2002-07-29 19:01:38 +00:00
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Normally the work remaining is between the high- and low-water
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marks. When the work remaining reaches the low-water mark, the core
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client contacts one or more scheduling servers, and attempts to get
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enough work to exceed the high-water mark. The scheduling server sends a
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maximum of four weeks of work. If a work unit is not feasible for a host
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because it consumes too many system resources, the scheduling server
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will not send that work unit.
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</p>
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2002-04-30 22:22:54 +00:00
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<p>
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2002-07-29 19:01:38 +00:00
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The amount of work (measured in FP/int ops) sent in a single
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scheduling RPC can be limited by the project, on a per-application
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basis.
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</p>
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2002-04-30 22:22:54 +00:00
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<p>
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2002-07-29 19:01:38 +00:00
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This scheme allows hosts that are sporadically connected (because
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they're portable or have modem-based connections) to avoid becoming idle
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due to lack of work.
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</p>
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2002-04-30 22:22:54 +00:00
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<p>
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2002-07-29 19:01:38 +00:00
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<b>To do</b>: per-workunit flag saying to return the result ASAP?
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</p>
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</body>
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</html>
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