CSE 30 -- Assignment 6

Sample solutions

There are two sample solutions. They differ in how the threads are scheduled, whether they start running as "run-pause-run-pause..." or "pause-run-pause-run...." This one is "run-pause-run-pause", and this one is "pause-run-pause-run".

Original Assignment Statement

Here are the files that you'll need to do assignment 6. Note that in header.mips, I allocated only two extra words in the thread structure for the priority. Any more should be unnecessary. You may, however, add more fields, but you must modify the corresponding driver.mips driver. When we test your code, we will use a driver that allocates 256 bytes of space for the thread state (this is an upper bound -- your code should not come close to needing this much).

The files are

header.mips

student.mips

driver.mips (see also driver.c)

driver2.mips (see also driver2.c)

driver3.mips (see also driver3.c)

The first driver is just the same as that used in assignment 5. The second driver tests thread priority. The third driver tests dynamic thread creation. You'll have to write your own driver to test locking. Rough C code for testing the lock code is available.

Sample output from running my sample solution (not provided) with the above drivers is now available. Output from an implementation that schedules the threads slightly differently, with the same set of drivers, is also available.

You may also want to look at the sample solution for assignment 5 as another starting point.

We tested with the following drivers:

The grade distribution is

124 students handed in assignment 6.

assignment 6 as a whole: mean  39.602
                         stdev 35.3735

w/o late adjustment: mean  40.25
                     stdev 35.3363

Excluding all-zero scores:

assignment 6 as a whole: mean  63.7747
                         stdev 21.7589

w/o late adjustment: mean  64.8182
                     stdev 20.4538

Per-problem statistics:

Num  1:  mean  10.201613
         stdev 9.783940
Num  2:  mean  3.991935
         stdev 6.155899
Num  3:  mean  6.000000
         stdev 8.041224
Num  4:  mean  8.790323
         stdev 8.361079
Num  5:  mean  11.266129
         stdev 9.672132


Per-problem statistics, omitting zero grades:

Num  1:  mean  18.880597
         stdev 3.646803
Num  2:  mean  8.684211
         stdev 6.456760
Num  3:  mean  14.307692
         stdev 5.943770
Num  4:  mean  15.138889
         stdev 4.928110
Num  5:  mean  19.136986
         stdev 2.877951

One thing we looked for was the ability for the threads package to be used by a long-running multithreaded program. If your dynamic thread creation just extended the thread table, this means that after 256 threads are created/initialized and then exited, the thread table fills up and the thread package will crash. It is much better to scan the table for an unused slot, where some previous thread had run and completed.

bsy+www@cs.ucsd.edu, last updated Mon Dec 14 02:34:30 PST 1998.

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