Messages in this thread |  | | Date | Tue, 6 Feb 2001 20:32:35 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait |
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On Tue, 6 Feb 2001, Ben LaHaise wrote:
> > > - make asynchronous io possible in the block layer. This is > > > impossible with the current ll_rw_block scheme and io request > > > plugging. > > > > why is it impossible? > > s/impossible/unpleasant/. ll_rw_blk blocks; it should be possible to > have a non blocking variant that does all of the setup in the caller's > context. [...]
sorry, but exactly what code are you comparing this to? The aio code you sent a few days ago does not do this either. (And you did not answer my questions regarding this issue.) What i saw is some scheme that at a point relies on keventd (a kernel thread) to do the blocking stuff. [or, unless i have misread the code, does the ->bmap() synchronously.]
indeed an asynchron ll_rw_block() is possible and desirable (and not hard at all - all structures are interrupt-safe already, opposed to the kiovec code), but this is only half of the story. What is the big issue for me is an async ->bmap(). And we wont access ext2fs data structures from IRQ handlers anytime soon - so true async IO right now is damn near impossible. No matter what the IO-submission interface is: kiobufs/kiovecs or bhs/requests.
Ingo
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