http:^^www.cs.washington.edu^homes^forman^seeit^
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EDU^HOMES^FORMAN^SEEIT^
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Date: Tue, 10 Dec 1996 03:36:31 GMTServer: NCSA/1.4.2Content-type: text/htmlLast-modified: Wed, 02 Oct 1996 18:18:37 GMTContent-length: 11310<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"><!-- This file was generated automatically using m4 convenience macros: http://www.cs.washington.edu/homes/forman/src/HMacros.m4--><html><head><title>George Forman: Dissertation Research</title><base href="http://www.cs.washington.edu/homes/forman/"><meta name="author" content="forman@cs.washington.edu"><link rev="made" href="mailto:forman@cs.washington.edu"></head><body><center><h1>George Forman: Dissertation Research</h1></center><!WA0><!WA0><!WA0><img alt="================ fractal bar ================" width=566 height=66 src="http://www.cs.washington.edu/homes/forman/lib/hr-fractal.star8.gif"><br><h2>Overview</h2>The current focus of my work is on constructing tools to aid in writingapplications that provide good interactive responsiveness even inenvironments where resource availability is hard to predict or is highlydynamic. Applications that depend on networking (even indirectly, such asthrough a networked file system) may encounter several orders of magnitude ofbandwidth variability in a mobile computing environment where the interfacecan switch between wireless and wired connections. Operating systems can noteffectively hide such great network variation; instead, applications need tobe flexible about their resource demands if they are to remain usable throughperiods of degraded service.<p><!WA1><!WA1><!WA1><img alt="[graphic: modem vs. Ethernet bandwidth]" width=579 height=182 border=1src="http://www.cs.washington.edu/homes/forman/seeit/bps.gif"><p>Towards this end, my dissertation research develops an application frameworkand runtime system to express and manage logical units of resource demand(concurrency and progressive-quality results), gaining responsiveness at theuser interface principally by trading off the short-term quality of theresponse. For further introductory material, please read the<!WA2><!WA2><!WA2><a href="http://www.cs.washington.edu/homes/forman/dissertation.abstract.html" >abstract to my dissertation</a>. The technical details are not yetavailable online.<br><br><!WA3><!WA3><!WA3><img alt="================ fractal bar ================" width=566 height=66 src="http://www.cs.washington.edu/homes/forman/lib/hr-fractal.star4.gif"><p> <b>These pages are no longer maintained</b><br><h2>Try out these demos yourself <font size=-1>(if you're running X Windows)</font> </h2>I have implemented a prototype system to test my ideas. It consists ofa set of language extensions to C++, a pre-processor to convert these intomulti-threaded C++ code, and a runtime system to manage the dynamic task graph.I have written three interactive applications using this prototype system: a library catalog database browser, a Mandelbrot fractal generator, and a Web browser for photo albums in an incremental-resolution .The latter two are available here for demonstration.<p>When system resources are plentiful, it's easy to get good response time.It's when resources are scarce that responsiveness support begins to help.So, each of these demos is designed to exceed the capacity of our localresources.<!WA4><!WA4><!WA4><FORM method=postaction="http://www.cs.washington.edu/htbin-post/unrestricted/forman/nph-run.demo"><ol> <li> Which program would you like to run?<p><INPUT type="radio" name="appname" value="Fractals" checked ><b>Fractal Explorer:</b> generates multiple Mandelbrot fractals incrementallyand concurrently, with the mouse position controlling priority among windows.<br><center> <!WA5><!WA5><!WA5><img alt="[screen dump of fractal explorer]" width=252 height=164 border=1src="http://www.cs.washington.edu/homes/forman/seeit/fractal.explorer.gif"></center><p><INPUT type="radio" name="appname" value="PhotoAlbum"><b>Photo Album Browser:</b> downloads a collection of photographs withprogressively improving quality & prioritization among pictures.<br><center> <!WA6><!WA6><!WA6><img alt="[screen dump of photo album browser]" width=493 height=89 border=1src="http://www.cs.washington.edu/homes/forman/seeit/photo.browser.gif"></center><br><br><li> To permit the application to connect to your display, execute the UNIX command<br><tt>xhost +trouble.cs.washington.edu</tt><br><br><li> Enter your display name (e.g. xterminal.u.washington.edu:0) or IP address (e.g. 12.34.56.78:0):<br><INPUT type="text" value="you.u.edu:0" name="DISPLAY"> <INPUT type="submit" value="Execute (read on while it starts up)"><br>TVTWM users: this demo tickles a fatal bug in tvtwm compiled for DEC Alphas.<p>Note: (1) These applications were meant to run near the user. If the delaybetween your X server and the application is large, you'll experience delayedresponsive performance, meaning that you can still control priority, etc.,but only slowly. (2) Other students sometime run large simulations on our departmentalhosts, bringing them to their knees. You'll know.</FORM></ol><br><h2>Things to notice and try...</h2><!WA7><!WA7><!WA7><img alt="================ fractal bar ================" width=566 height=66 src="http://www.cs.washington.edu/homes/forman/lib/hr-fractal.star2.gif"><h3>Fractal Explorer Demo:</h3><OL><LI> First, after reading the directions for operating the program, noticethat you can zoom in on a fractal while it is still refining. This abilityto proceed with only an incomplete result becomes more important asvariability in system response time increases. Today, such a feature is onlyimplemented for those tasks that are expected to take a long time, but assystem service time increases in variability this feature needs to beimplemented for more and more tasks.<LI> Try zooming in on two fractal windows in rapid succession so that theyare simultaneously refining their images, then move the mouse over one ofthem. Notice that the application concentrates its resources on the selectedfractal. The other fractal may get some CPU attention when the primary isblocked for I/O or thread synchronization.<LI> Now try the same, but point the mouse outside both windows. Observethat the two fractals improve in resolution at roughly the same rate,roughly half as fast as before.<LI> To try the color enhancement feature, first zoom in on a part of thefractal <!WA8><!WA8><!WA8><img alt="[low contrast fractal]" width=71 height=46 align=rightsrc="http://www.cs.washington.edu/homes/forman/seeit/lo.contrast.gif"> that has little variation in color, then quickly type 'c' to re-colorit. This runs the entire image through a histogram equalization function(it's slow). Notice that this function is run on the successive imagesproduced by the fractal generator.<LI> To illustrate what is going on inside the application, do the followingin rapid succession: zoom on an area, set the toggle button to open a newwindow when zooming, then type 'c'. A new window will display the re-coloredversion of the first window.<br><br> <!WA9><!WA9><!WA9><img alt="[diagram of task graph]" width=234 height=195 align=right border=1src="http://www.cs.washington.edu/homes/forman/seeit/tgraph.gif"> This diagram illustrates the task graph that was generated by thissequence of user events; the green tasks were added when you typed 'c'. Theoutput from the fractal image generator is consumed both by a display taskfor the first window and by a re-coloring task whose output goes to a seconddisplay task for the other window. A series of refined images passes throughthis data-flow graph.<LI> When a portion of the task graph becomes disconnected from a usefuloutput (such as the display or an internal program variable), the runtimesystem prunes it from the graph and garbage collects its associated storage.This happens when you zoom in on a fractal that is still refining. You can'twitness this at the user interface, except that the resource savings improvethe performance of the tasks that you care about.</OL><!WA10><!WA10><!WA10><img alt="================ fractal bar ================" width=566 height=66 src="http://www.cs.washington.edu/homes/forman/lib/hr-fractal.star.gif"><h3>Photo Album Browser Demo:</h3>Suppose you want to show a friend at lunch a particular photograph of yourbaby, so you pull out your mobile computer and access your home photo albumvia the wireless network. Given that downloading all your baby pictureswould take a long time, you want a photo album browser that downloads anddisplays images incrementally, and that prioritizes bandwidth consumptionamong the photos as you search for the picture. Imagine this scenario as youuse the browser- try to find the sunset photograph quickly. Keep in mindthat the Internet provides higher bandwidth than a wireless network. Also,the effect of prioritization becomes much more pronounced when the desiredpriorities for the various network connections are communicated to thewireless base station. This has been implemented in an experimental setup,but is not available for demo on the Web.<OL><LI> To observe the effect of priority, press return in the URL window torestart the downloads, then quickly open two pictures and move the mouseover the later one. Observe that the selected picture gets refined fasterthan the other; this is more obvious in later refinements when the resolutionis finer. Each refinement quadruples the number of pixels in the image.<LI> The application pre-fetches one picture off the edge of the strip. Toobserve this, restart the downloads, wait for a few resolution improvements& note which picture is rightmost on the strip, then scroll to the righta few pictures. Notice the difference in resolution of the first picture tothe right vs. the others.</OL><!-- Signature line follows: --><br> <br> <!WA11><!WA11><!WA11><img alt="================================================================" width=600 height=5 src="http://www.cs.washington.edu/homes/forman/lib/hr-rainbow.gif"><br> <address>George H. Forman, gforman@hpl.hp.com<br><!WA12><!WA12><!WA12><a href="http://www.cs.washington.edu/homes/forman/">home page</a><!WA13><!WA13><!WA13><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"> <!WA14><!WA14><!WA14><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"><!WA15><!WA15><!WA15><a href="mailto:gforman@hpl.hp.com">mail</a><!WA16><!WA16><!WA16><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"> <!WA17><!WA17><!WA17><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"><!WA18><!WA18><!WA18><a href="http://www.cs.indiana.edu/finger/pugsly.cs.washington.edu/forman">finger</a><!WA19><!WA19><!WA19><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"> <!WA20><!WA20><!WA20><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"><!WA21><!WA21><!WA21><a href="http://wings.buffalo.edu/cgi/xeroxgw?Seattle+WA&47&36&122&19">map</a><!WA22><!WA22><!WA22><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"> <!WA23><!WA23><!WA23><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"><!WA24><!WA24><!WA24><a href="http://www.nnic.noaa.gov/cgi-bin/forecast.do-it?search=Seattle&state=Washington&html=yes&area=Local">weather</a><!WA25><!WA25><!WA25><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"> <!WA26><!WA26><!WA26><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"><!WA27><!WA27><!WA27><a href="http://www.cs.washington.edu/">CS Dept.</a><!WA28><!WA28><!WA28><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"> <!WA29><!WA29><!WA29><img alt=" " width=1 height=1 src="http://www.cs.washington.edu/homes/forman/lib/dot_clear.gif"><!WA30><!WA30><!WA30><a href="http://www.washington.edu/">UW (live picture)</a></address><br> Generated: Wed Oct 2 11:18:37 PDT 1996</body> </html>⌨️ 快捷键说明
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