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    SubjectRe: [PATCH] Document Linux's memory barriers
    Date
    On Tuesday 7 March 2006 21:09, David Howells wrote:
    > Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
    >
    > > Better meaningful example would be barriers versus an IRQ handler. Which
    > > leads nicely onto section 2
    >
    > Yes, except that I can't think of one that's feasible that doesn't have to do
    > with I/O - which isn't a problem if you are using the proper accessor
    > functions.
    >
    > Such an example has to involve more than one CPU, because you don't tend to
    > get memory/memory ordering problems on UP.

    On UP you at least need compiler barriers, right? You're in trouble if you think
    you are writing in a certain order, and expect to see the same order from an
    interrupt handler, but the compiler decided to rearrange the order of the writes...

    > The obvious one might be circular buffers, except there's no problem there
    > provided you have a memory barrier between accessing the buffer and updating
    > your pointer into it.
    >
    > David

    Ciao,

    Duncan.
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