lkml.org 
[lkml]   [2000]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Timestamp counters on SMP
> see comments there. In general, I don't think you should count on TSC's
> being syncronized at all - some people have computers with TSC's of
> different rates (me included).

in this case, TSC is completely and utterly useless to user-space.
there are only three sensible alternatives:
- TSC's are incoherent and TSC's are turned off in user-space.
- TSC's can be relied upon, and the kernel syncs them.
- the kernel saves/restores TSC contents as necessary to make
user-space see coherent time. ouch!

the sanity of SMP with different clocks is ambiguously in any case:
the MPS standard says that OS's should merely try to function,
but doesn't mandate any particular or sensible user-space behavior.

regards, mark hahn.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:57    [W:0.075 / U:0.684 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site