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    SubjectRe: [patch rfc] towards supporting O_NONBLOCK on regular files
    ==> Regarding Re: [patch rfc] towards supporting O_NONBLOCK on regular files; "Stephen C. Tweedie" <sct@redhat.com> adds:

    sct> Hi, On Thu, 2004-10-07 at 11:12, Marcelo Tosatti wrote:

    >> Oh yes, theres also the indirect blocks which we might need to read from
    >> disk.

    sct> Right.

    >> Now the question is, how strict should the O_NONBLOCK implementation be
    >> in reference to "not blocking" ?

    sct> Well, I suspect that depends on the application. But if you've got an
    sct> app that really wants to make sure its hot path is as fast as possible
    sct> (eg. a high-throughput server multiplexing disk IO and networking
    sct> through a single event loop), then ideally the app would want to punt
    sct> any blocking disk IO to another thread.

    sct> So it's a matter of significant extra programing for a small extra
    sct> reduction in app blocking potential.

    sct> I think it's worth getting this right in the long term, though.
    sct> Getting readahead of indirect blocks right has other benefits too ---
    sct> eg. we may be able to fix the situation where we end up trying to read
    sct> indirect blocks before we've even submitted the IO for the previous
    sct> data blocks, breaking the IO pipeline ordering.

    So for the short term, are you an advocate of the patch posted?

    -Jeff
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