Messages in this thread | | | From | David Howells <> | Subject | Re: [PATCH] slow_work_thread() should do the exclusive wait | Date | Thu, 16 Apr 2009 10:10:18 +0100 |
| |
Andrew Morton <akpm@linux-foundation.org> wrote:
> The patch itself is a little worrisome. The wake-all semantics are > very good at covering up little race bugs. And switching to wake-once > is a great way of exposing hitherto-unsuspected races.
It's something I'm intending to test, once I get MN10300 working again (which for some reason it isn't).
> I wonder if slow_work_cull_timeout() should have some sort of barrier, > so the write is suitably visible to the woken thread.
That's an interesting question. Should wake_up() imply a barrier of any sort, I wonder. Well, __wake_up() does impose a barrier as it uses a spinlock, but I wonder if that's sufficient.
> Bearing in mind that the thread might _already_ have been woken by someone > else?
If the thread is woken by someone else, there must be work for it to do, in which case it wouldn't be culled anyway.
> off-topic: afacit the code will cull a maximum of one thread per five > seconds. But the rate of thread _creation_ is, afacit, unbound. Are > there scenarios in which we can get a runaway thread count?
The maximum number of threads is limited (slow_work_max_threads).
David
| |