From mboxrd@z Thu Jan  1 00:00:00 1970
From: danc@iobjects.com (Dan Conti)
To: "Jonathan Larmour" <jlarmour@redhat.com>, <ecos-discuss@sources.redhat.com>
Subject: RE: [ECOS] Unique priorities
Date: Thu, 11 Jan 2001 09:31:00 -0000
Message-id: <LHEHKGCFEPABLCKPPMGLOEPCCBAA.danc@iobjects.com>
References: <3A5DE5C4.33B37AA0@redhat.com>
X-SW-Source: 2001-01/msg00191.html

>From what i can see, it does a ++ on the priority if the given priority is
taken (from bitmap.cxx):

Cyg_SchedThread_Implementation::Cyg_SchedThread_Implementation
(
    CYG_ADDRWORD sched_info
)
{
    CYG_REPORT_FUNCTION();

#if 1
    // Assign this thread's priority to the supplied sched_info
    // or the next highest priority available.

    priority = cyg_priority(sched_info);

    while( !Cyg_Scheduler::scheduler.unique(priority) )
        priority++;

#else
    // Assign initial priorities to threads in descending order of
    // creation.

    static cyg_priority init_priority = 0;

    priority = init_priority++;
#endif

}


-Dan


-----Original Message-----
From: ecos-discuss-owner@sources.redhat.com
[ mailto:ecos-discuss-owner@sources.redhat.com]On Behalf Of Jonathan
Larmour
Sent: Thursday, January 11, 2001 8:57 AM
To: Jesper Skov
Cc: Paleologos Spanos; ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] Unique priorities


Jesper Skov wrote:
>
> >>>>> "Paleologos" == Paleologos Spanos <paleolog@ee.ucla.edu> writes:
> Paleologos> mlqueues default scheduler).  I would expect that I would
> Paleologos> have an error or something like that because of the fact
> Paleologos> that the 2 threads are having the same priority (4).Is it
> Paleologos> correct or I have misunderstood something?
>
> The bitmap scheduler will assign a thread the closest possible
> priority to that requested. It does not fail if the requested priority
> is already used, it just returns another. So your threads would
> probably have priorities 4 and 5.

Jesper are you sure about that? From bitmap.cxx

void Cyg_Scheduler_Implementation::add_thread(Cyg_Thread *thread)
{
    CYG_REPORT_FUNCTION();

    CYG_ASSERT((CYG_THREAD_MIN_PRIORITY >= thread->priority)
               && (CYG_THREAD_MAX_PRIORITY <= thread->priority),
               "Priority out of range!");

    CYG_ASSERT( thread_table[thread->priority] == NULL ||
                thread_table[thread->priority] == thread,
                "Duplicate thread priorities" );

Jifl
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