Messages in this thread | | | Date | Sun, 10 Oct 1999 20:42:31 +0200 | From | Manfred Spraul <> | Subject | Re: locking question: do_mmap(), do_munmap() |
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Alexander Viro wrote: > I'm not sure that it will work (we scan the thing in many places and > quite a few may be blocking ;-/), unless you propose to protect individual > steps of the scan, which will give you lots of overhead.
The overhead should be low, we could keep the "double synchronization", ie * either down(&mm->mmap_sem) or spin_lock(&mm->vma_list_lock) for read * both locks for write.
I think that 3 to 5 spin_lock() calls are required.
> I suspect that > swap_out_mm() needs fixing, not everything else... And it looks like we > can't drop the sucker earlier in handle_mm_fault. Or can we?
That would be a good idea: For multi-threaded applications, swap-in is currently single-threaded, ie we do not overlap the io operations if 2 threads of the same process cause page faults. Everything is fully serialized.
But I think this would be a huge change, eg do_munmap() in one thread while another thread waits for page-in....
-- Manfred
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