Global Timer Issue

[Nessphoro]

Hello, mates,

I've got my multitasking working and it is working - well nice enough.
Now I encountered a "how is this even possible" kind of issue.
So basically, I have three threads that just "hlt" in a loop - their page directories are all linked above 3Gb mark and each has its own stack.
My IRQ0 event handler looks like this:

Code: Select all

           Ticks++;
            if(Ticks%1000==0)
            {
                *Graphics::GetConsole()<<Ticks<<endl;
            }
            ...

The problem is, every 1000 ticks( 1 second) I get three lines in the console of identical value. Four if I have four threads running, and so forth.

Any ideas on how it's possible? I have verified that Ticks points to the same physical address in all threads, and also interrupts are disabled in the IRQ stub.

[bluemoon]

Is Ticks thread safe?
How do you invoke the scheduler (before or after print Ticks?) and how it work?

[Nessphoro]

Aye, ticks are volatile.
Scheduler is invoked after the print, and it will delay the switch until the end (iret) where a small routine will switch address space and esp and restore the registers