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    SubjectRe: [PATCH] Syslets - Fix cachemiss_thread return value
    On Thu, May 31, 2007 at 03:07:16PM -0700, Zach Brown wrote:
    > Can you explain what motivated you to send out this patch?
    >
    > It used to return 0. It was changed because, unlike the syslet
    > syscalls, sys_io_submit() doesn't have a simple 0 value to indicate
    > success. The current implementation wants to return the number of iocbs
    > that were processed, including the one which blocked, from the cachemiss
    > thread. So before calling into an operation it sets task_ret_ret() so
    > that the cachemiss thread can return it if it takes over.
    > task_ret_reg() is holding a return value that is being returned by the
    > cachemiss thread on behalf of a sys_io_submit() which blocked.
    >
    > When I made the change I didn't really audit its effect on the other
    > paths. I suppose it's time to do that, and you could help by telling me
    > if you saw something bad happen :).

    The bad thing was sys_async_exec returning -NOSYS every time a new
    cachemiss thread was created.

    Without this patch, you'll see sys_async_exec failures with either of
    the demos I sent out. Dunno about the existing ones, but I bet they do
    the same.

    Jeff

    --
    Work email - jdike at linux dot intel dot com
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