X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2F44bsd.texi;h=f1638f80d31daae0739a263d7e5ddaa02583a2b7;hb=ed04361f6ec91e4f0db1550c2cc487a461b2d17b;hp=d27343f655d979540f74b1243fcffb4000e6bbe8;hpb=b492098dbb2bd50aef4104bcef418ba53f30a4eb;p=pintos-anon diff --git a/doc/44bsd.texi b/doc/44bsd.texi index d27343f..f1638f8 100644 --- a/doc/44bsd.texi +++ b/doc/44bsd.texi @@ -113,7 +113,9 @@ the formula @noindent where @var{recent_cpu} is an estimate of the CPU time the thread has used recently (see below) and @var{nice} is the thread's -@var{nice} value. The coefficients @math{1/4} and 2 on @var{recent_cpu} +@var{nice} value. The result should be rounded down to the nearest +integer (truncated). +The coefficients @math{1/4} and 2 on @var{recent_cpu} and @var{nice}, respectively, have been found to work well in practice but lack deeper meaning. The calculated @var{priority} is always adjusted to lie in the valid range @code{PRI_MIN} to @code{PRI_MAX}. @@ -182,7 +184,7 @@ current value of @var{recent_cpu} decays to a weight of .1 in received ``recently,'' with the rate of decay inversely proportional to the number of threads competing for the CPU. -Assumptions made by some of the tests require that updates to +Assumptions made by some of the tests require that these recalculations of @var{recent_cpu} be made exactly when the system tick counter reaches a multiple of a second, that is, when @code{timer_ticks () % TIMER_FREQ == 0}, and not at any other time.