Re: why spinlock raises IRQL to DISPATCH

Because a spinlock has other threads spin on the lock. If you do not
disable scheduling you can create a situation where most of your systems CPU
time is spent spinning on locks, and where a low priority thread has
acquired the lock then is starved by spinning to the point that it taks a
long time to release it.

Spin locks are spupposed to be low overhead locks for short periods of use.
Note: on a uniprocessor implementation the lock is never set, the
implementation is just raise to dispatch to disable scheduling.


--
Don Burn (MVP, Windows DDK)
Windows 2k/XP/2k3 Filesystem and Driver Consulting
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"Bajamani" <bajamani@xxxxxxxxxxx> wrote in message
news:1116246989.835297.82030@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Why does spinlock implementation raise the irql to dispatch level? just
> acquiring the lock at passive level should prevent other threads from
> accessing the same lock.
>


.

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