[prev in list] [next in list] [prev in thread] [next in thread] 

List:       haiku-bugs
Subject:    Re: [Haiku-bugs] [Haiku] #1993: Implement using HPET timers and
From:       "Haiku" <trac () haiku-os ! org>
Date:       2008-03-31 11:22:26
Message-ID: 049.485c4f8f14d49c73ab40061285286c08 () haiku-os ! org
[Download RAW message or body]

#1993: Implement using HPET timers and other mechanisms than TSC for time keeping
--------------------------+-------------------------------------------------
  Reporter:  axeld        |       Owner:  axeld         
      Type:  enhancement  |      Status:  new           
  Priority:  high         |   Milestone:  R1            
 Component:  - General    |     Version:  R1 development
Resolution:               |    Platform:  All           
--------------------------+-------------------------------------------------
Comment (by mmlr):

 Just to document that: In fact the same mechanism as in the cpu_fix driver
 can be used to "resync" the system time after a frequency change. By
 adjusting the conversion factor and the time base the system_time() can be
 made reliable without interruption
 (http://beos.mlotz.ch/documents/cpu_fix.html). So the only thing that is a
 problem are unsynchronized TSCs across multiple cores/processors. As far
 as I know though only certain AMD multi core processors do not provide an
 invariant TSC across the cores (as described in the lkml message you
 linked). I mention that since using the CPU internal rdtsc is desirable
 for performance reasons and therefore should be used when possible.

-- 
Ticket URL: <http://dev.haiku-os.org/ticket/1993#comment:4>
Haiku <http://dev.haiku-os.org>
The Haiku operating system.
_______________________________________________
Haiku-bugs mailing list
Haiku-bugs@lists.berlios.de
https://lists.berlios.de/mailman/listinfo/haiku-bugs
[prev in list] [next in list] [prev in thread] [next in thread]