[ck] Re: Threading issues? [ck-request@vds.kolivas.org: ck Digest, Vol 3, Issue 16]

Ove Kaaven ovek at arcticnet.no
Sun Aug 29 06:26:01 CDT 2004

søn, 29.08.2004 kl. 11.43 skrev Robert Shearman:
> Ove Kaaven wrote:
> >søn, 29.08.2004 kl. 04.13 skrev Michael Chang:
> >  
> >
> >Also note that Windows allows a Win32 process to boost its own priority
> >all the way to what they call "real time". Only root can do this under
> >Linux. I'm not sure if you need administrator privileges to do this
> >under Windows (probably not), but since every Windows user runs as
> >administrator anyway, it's probably not unlikely that many applications
> >expect this ability anyway.
> >
> As decribed here:
> http://www.winntmag.com/Articles/Index.cfm?IssueID=22&ArticleID=302
> There are 31 priority levels and only users with Administrator 
> privileges can set processes to the highest priorities of 16-31.

OK, so you need administrator to set a realtime priority, but you are
still able to set a high priority on yourself without being an
administrator under Windows. This is not possible under Linux, where a
non-root process can only reduce, not elevate, its own priority.

> I doubt there are programs that require these high priorities, although 
> we could find potential targets by printing a message for programs that 
> try and set their priority to a high level.

For what it's worth, at TransGaming we know for a fact that some games
(maybe it was Battlefield 1942) does; they elevate the priority of one
of their most critical threads, and seem to use interesting mechanisms
to regulate how much time this high-priority thread use relative to the
other threads. In any case it does help the game's smoothness to
experimentally elevate this thread's priority under Linux, but this is
not really a solution because of permissions.

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