Re: Linux 2.4.21-rc7

From: Willy Tarreau (
Date: Sun Jun 08 2003 - 16:47:11 EST

> Note that "nodma" is unnecessary on this
> same box running kernel 2.4.19-rc2. Why would
> 2.4.21-rcX need it? To pin down whether the
> problem is in the ide dma code or some other
> part of the ide code?

exactly, because DMA needs more conditions than PIO to run at all
and even more to run reliably. There are lots of cases where DMA
doesn't work while PIO does.
> It does not die more easily with 2.4.19-rc2
> (in my opinion). It dies in a threads context
> but not in a forks context, where the threads
> and the forks are doing the same i/o to/from
> the same controller/disk (different versions
> of same program).
> I have also seen it freeze with an unlucky
> mouse click in XFree86 4.0 under 2.4.19-rc2,
> so I did not assume that the threads hang
> was necessarily ide-relevant. Something
> disk i/o intensive was merely what it
> happened to be doing with those threads,
> but that problem seemed to me more thread
> related than ide related. (Guess I'll have
> to spawn a bunch of threads doing some other
> kind of i/o to test that assumption.)

OK, but a freeze isn't acceptable anyway, whatever you were doing,
because it always means a bug somewhere.


PS: your lines were shorter this way :-)

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