Re: [Algorithms] General purpose task parallel threading approach

[Jarkko L. <al...@gm...>]

With job stealing from other threads you don't get global prioritization, so
one task may be executing lower priority tasks and not to work towards
optimal throughput.

 

 

Cheers, Jarkko

 

  _____  

From: Sebastian Sylvan [mailto:seb...@gm...] 
Sent: Sunday, April 05, 2009 4:32 AM
To: Game Development Algorithms
Subject: Re: [Algorithms] General purpose task parallel threading approach

 

 

On Sun, Apr 5, 2009 at 2:11 AM, Jarkko Lempiainen <al...@gm...> wrote:

Sub-tasks spawn by a task are not necessarily run serially by the same
worker thread though. Worker threads should pull tasks from job queue based
on task priority, so those spawned tasks are likely to be executed by many
worker threads instead.

That's probably not a good idea. Work-stealing is a pretty well-established
as the current best solution (with provable performance properties) for
task-based parallelism as it combines locality with low contention and still
gets optimal load-balancing.

Going to shared queue every single task (and probably incurring a cache miss
if the task is unrelated to what you were just doing) is a lot more costly
than just pushing tasks off of your own mostly private stack (and only
interfering with other threads when you and they run out of stuff to do
simultaneously).

 

-- 
Sebastian Sylvan
+44(0)7857-300802
UIN: 44640862