X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fthreads.texi;h=a28d7a41d1c14842c8ee65a8ca3bf26c177c4ff8;hb=34ff639aaa7fd691d2e588d46acd41669c0b5754;hp=432cb2668224dab21a7be7164d476324cf2ad63d;hpb=569a896c533bcc20efa5883d491bfaa5839ffb7c;p=pintos-anon diff --git a/doc/threads.texi b/doc/threads.texi index 432cb26..a28d7a4 100644 --- a/doc/threads.texi +++ b/doc/threads.texi @@ -328,9 +328,10 @@ timer ticks or input events. Turning off interrupts also increases the interrupt handling latency, which can make a machine feel sluggish if taken too far. -You may need to add or modify code where interrupts are already -disabled, such as in @func{sema_up} or @func{sema_down}. You should -still try to keep this code as short as you can. +The synchronization primitives themselves in @file{synch.c} are +implemented by disabling interrupts. You may need to increase the +amount of code that runs with interrupts disabled here, but you should +still try to keep it to a minimum. Disabling interrupts can be useful for debugging, if you want to make sure that a section of code is not interrupted. You should remove @@ -441,8 +442,8 @@ priority such that it no longer has the highest priority must cause it to immediately yield the CPU. Thread priorities range from @code{PRI_MIN} (0) to @code{PRI_MAX} (63). -Lower numbers correspond to @emph{higher} priorities, so that priority 0 -is the highest priority and priority 63 is the lowest. +Lower numbers correspond to lower priorities, so that priority 0 +is the lowest priority and priority 63 is the highest. The initial thread priority is passed as an argument to @func{thread_create}. If there's no reason to choose another priority, use @code{PRI_DEFAULT} (31). The @code{PRI_} macros are @@ -674,7 +675,7 @@ list. @item If the highest-priority thread yields, does it continue running? -Yes. As long as there is a single highest-priority thread, it continues +Yes. If there is a single highest-priority thread, it continues running until it blocks or finishes, even if it calls @func{thread_yield}. If multiple threads have the same highest priority, @@ -684,8 +685,8 @@ If multiple threads have the same highest priority, Priority donation only changes the priority of the donee thread. The donor thread's priority is unchanged. -Priority donation is not additive: if thread @var{A} (with priority 3) donates -to thread @var{B} (with priority 5), then @var{B}'s new priority is 3, not 8. +Priority donation is not additive: if thread @var{A} (with priority 5) donates +to thread @var{B} (with priority 3), then @var{B}'s new priority is 5, not 8. @item Can a thread's priority change while it is on the ready queue? @@ -729,9 +730,6 @@ scheduler at the same time. @item Can I use one queue instead of 64 queues? -Yes, that's fine. It's easiest to describe the algorithm in terms of 64 -separate queues, but that doesn't mean you have to implement it that -way. - -If you use a single queue, it should probably be sorted. +Yes. In general, your implementation may differ from the description, +as long as its behavior is the same. @end table