Messages in this thread |  | | Date | Thu, 15 Aug 2002 11:31:48 +0100 | From | Jamie Lokier <> | Subject | Re: [patch] user-vm-unlock-2.5.31-A2 |
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Ingo Molnar wrote: > > I wonder if it makes more sense for the release word to be a futex -- > > then various ways of actually waiting for the stack are available. > > the window for locking is really small (and will always be small), so it's > cheaper for the fastpath to implement this as a spinlock, with the > stack-user being the lock holder.
I'm thinking that any _clean_ threading library (pthreads or not) should do these two things:
- intercept all the system calls that might call mmput(); that is, exit() and execve()), just so it can move the thread-specific data (including the stack) onto the "potentially free list".
- free the stack memory as soon as possible after a thread has died, _without_ depending on garbage collection. What if all the other threads are compute-bound? There's a lump of unnecessary stack taking up memory for an indefinite time.
It seems that you're using a futex anyway -- so why not eliminate that pesky system call _and_ make sure pthread_join() work if some library you're linked to exits without calling pthread_exit()..
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