Messages in this thread | | | Date | Thu, 21 Sep 2006 00:32:22 -0700 | Subject | Re: [PATCH] move put_task_struct() reaping into a thread [Re: 2.6.18-rt1] | From | Bill Huey (hui) <> |
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On Thu, Sep 21, 2006 at 09:16:24AM +0200, Ingo Molnar wrote: > * Bill Huey <billh@gnuppy.monkey.org> wrote: > > It's correct from the standpoint of it being reaped in another thread, > > so it fixed those crashes. But I pushed it down into another thread at > > the request of Esben and his private discussion with Paul McKenney, > > since a summary from Esben felt that call_rcu() was somehow less than > > ideal to do that. > > but it _is_ already being reaped in another thread: softirq-rcu. > Splitting that up any further will only fragment the context-switching > and increases cache footprint - it wont (or rather, shouldnt) have any > functional effect. (As a sidenote, i'm considering the unification of > all 'same default priority' softirq threads into a single thread per > CPU, to further reduce this cost of 'spreadout'.)
I overloaded another reaping thread that was doing largely similar functionality in that it was also reaping, so I don't think it's that bad. I did it from a cleanliness point of view with the code tree. It's the "desched_thread" in fork.c that I'm using. It seems to be the right thing to do. I'm sure Esben will follow up on this.
> > > that you saw crashes under 2.6.17 - but did you manage to figure out > > > what the reason is for those crashes, and do those reasons really > > > necessiate the pushing of task-reapdown into yet another set of > > > kernel threads? > > > > Unfortunately no. I even used Robert's .config on my machine. I added > > a disk controller and networking device driver just to boot into his > > configuration and I still couldn't replicated any of his kjournald > > problems at all. If I had his hardware I'd have a better way of > > replicating those problems and pound it out. > > ok, then i guess what we have left is to wait and see whether it still > triggers with the current 2.6.18-rt codebase - maybe it triggers for > someone in a scenario that is easier to debug.
bill
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