A Simpler Find Tool

A Simpler Find Tool

[Brian Kolden]

I made a simple find tool for Linux, https://github.com/bkold/finda, and I was wondering if I could optimize the task scheduling a bit. 

	protected body Task_Pool_Status is
		procedure Check (Thread_Pointer : out Thread_Access) is
		begin
			for I in Status'Range loop
				if Status(I) = Ready then
					Status(I) := Working;
					Thread_Pointer := Threads(I);
					return;
				end if;
			end loop;
			Thread_Pointer := Null;
		end Check;

		procedure End_Thread (Thread_Num : in CPU) is
		begin
			Status(Thread_Num) := Ready;
		end End_Thread;
	end Task_Pool_Status;

I'm using a request and reserve model to determine which threads are waiting and which are busy. The threads call End_Thread when they finish their work in order to be available to be queued again. I think the model itself is good, but I was unhappy with how I find the sleeping threads. Does anyone have a cleaner suggestion?

Re: A Simpler Find Tool

[Simon Wright]

Brian Kolden <bakolden5@gmail.com> writes:

> I made a simple find tool for Linux, https://github.com/bkold/finda,
> and I was wondering if I could optimize the task scheduling a bit.
>
> 	protected body Task_Pool_Status is
> 		procedure Check (Thread_Pointer : out Thread_Access) is
> 		begin
> 			for I in Status'Range loop
> 				if Status(I) = Ready then
> 					Status(I) := Working;
> 					Thread_Pointer := Threads(I);
> 					return;
> 				end if;
> 			end loop;
> 			Thread_Pointer := Null;
> 		end Check;
>
> 		procedure End_Thread (Thread_Num : in CPU) is
> 		begin
> 			Status(Thread_Num) := Ready;
> 		end End_Thread;
> 	end Task_Pool_Status;
>
> I'm using a request and reserve model to determine which threads are
> waiting and which are busy. The threads call End_Thread when they
> finish their work in order to be available to be queued again. I think
> the model itself is good, but I was unhappy with how I find the
> sleeping threads. Does anyone have a cleaner suggestion?

Just how many threads are you expecting to have? Is it worth saving some
cycles here?

You could have a queue of Ready threads, pop a thread when required,
push when done. That would allow you to have an entry, which would save
the polling?

   entry Get (A_Thread : out Thread_Access) when Queue.Head /= null
   is

Re: A Simpler Find Tool

[G.B.]

On 21.05.17 07:04, Brian Kolden wrote:
> Does anyone have a cleaner suggestion?

Not answering directly, but did you have a look at how
the Paraffin library handles this? (Available at
BIZX Company's SourceForge subsidiary.)

Re: A Simpler Find Tool

[Jeffrey R. Carter]

On 05/21/2017 07:04 AM, Brian Kolden wrote:
>
> I'm using a request and reserve model to determine which threads are waiting
> and which are busy. The threads call End_Thread when they finish their work
> in order to be available to be queued again. I think the model itself is
> good, but I was unhappy with how I find the sleeping threads. Does anyone
> have a cleaner suggestion?

This feels backward to me. In Ada, tasks schedule themselves, so it seems more 
natural for the task to wait until there's work to do and then do it than for 
the work to look for an available task.

I'd suggest you replace your task pool with an instance of PragmARC.Job_Pools.

The PragmAda Reusable Components are available from

https://pragmada.x10hosting.com/

and

https://github.com/jrcarter/PragmARC

-- 
Jeff Carter
"I soiled my armor, I was so scared."
Monty Python & the Holy Grail
71

Re: A Simpler Find Tool

[Brian Kolden]

> Just how many threads are you expecting to have? Is it worth saving some
> cycles here?

It's being called almost constantly, so yes.
 
> You could have a queue of Ready threads, pop a thread when required,
> push when done. That would allow you to have an entry, which would save
> the polling?
> 
>    entry Get (A_Thread : out Thread_Access) when Queue.Head /= null
>    is

I don't know why I didn't think to do that. It's using a stack now.