Re: O_DIRECT question

[Phillip Susi]

Mark Lord wrote:
> You guys need to backup in this thread.
>
> Every example of O_DIRECT here could be replaced with
> calls to mmap(), msync(), and madvise() (or posix_fadvise).
>
> In addition to being at least as fast as O_DIRECT,
> these have the added benefit of using the page cache (avoiding reads for 
> data already present, handling multiple
> users of the same data, etc..).

Please actually _read_ the thread.  In every one of my posts I have 
shown why this is not the case.

To briefly rehash the core of the argument, there is no way to 
asynchronously manage IO with mmap, msync, madvise -- instead you take 
page faults or otherwise block, thus stalling the pipeline.

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