RE: [Geekos-devel] Efficient implementing of semaphores...

[Jaime Lafleur-V. <jv...@wa...>]

Yes, indeed there is.
 
Most architectures provide at least one atomic instruction that would
enable you to implement critical sections and semaphore without having
to resort to disabling interrupts.
 
Example instructions that the hardware may provide atomically are:
            Test-and-set: operates on 1 bit of memory. Returns the
previous value and sets the bit to 1.
            Swap: swaps to input values
 
Since these operations would be atomic, they could be used to enforce a
critical section.
 
In GeekOS disabling of interrupts for atomicity is used in many places
because the time period where interrupts are disabled is so small that
it has little or no negative effect. Thus, I wouldn't be concerned with
disabling of interrupts as long as the period is short. 
 
Jaime
 
-----Original Message-----
From: gee...@li...
[mailto:gee...@li...] On Behalf Of Behrang
Saeedzadeh
Sent: Sunday, February 02, 2003 1:19 PM
To: GeekOS
Subject: [Geekos-devel] Efficient implementing of semaphores...
 
Is there any other ways for implementing semaphore primitives rather
than disabling interrupts in IA32?
Thanks in advance.
 
  _____  

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