Re: accel handling

James Simmons
1999-08-30T01:14:11Z

> You really need to have a cooperative locking engine. Doing this sort
> of thing by playing VM tricks is not acceptable: you are just making the
> driver side of things simpler by placing a whole extra lot of work onto
> the VM, and things will not necessarily go any faster.
>
> The real problem with a VM solution is that threaded applications on a
> multi-processor machine will go *immensely* slower. Every time you need
> to lock out a VM region, you have to send a storm of interrupts to the
> other CPUs to make sure they aren't in the middle of accessing the same
> region from a related thread. In general, any solution which requires
> fast twiddling of VM to make this work just will not be accepted.

I though so but I wanted to see if their was a acceptable trick to handle
this.

> A combination of shared-memory spinlocks (for fast tight-loop locking)
> and SysV semaphores (for a blocking lock if the lock is taken for too
> long) can be combined to give a simple but very efficient locking engine
> for this type of thing.

Any docs on this stuff. How would I go about do this ? I really want to do
this write.