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    SubjectRe: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3

    * Michael K. Edwards <medwards.linux@gmail.com> wrote:

    > [...] As for threadlets, making them kernel threads is not such a good
    > design feature, O(1) scheduler or not. You take the full hit of
    > kernel task creation, on the spot, for every threadlet that blocks.
    > [...]

    this is very much not how they work. Threadlets share the same basic
    infrastructure with syslets and they do /not/ take a 'full hit of kernel
    thread creation' when they block. Please read the announcements, past
    discussions on lkml and the code about how it works.

    about your other point:

    > > threadlets, when they block, are regular kernel threads, so the
    > > regular O(1) scheduler takes care of them. If MMU trashing is of any
    > > concern then syslets should be used to implement the most
    > > performance-critical events: under Linux a kernel thread that does
    > > not exit out to user-space does not do any TLB switching at all.
    > > (even if there are multiple processes active and their syslets
    > > intermix)
    >
    > As far as I am concerned syslets by themselves are a dead letter,
    > because you can't do any of the things that potential application
    > coders need to do with them. [...]

    syslets are not meant to be directly exposed to application coders.
    Syslets (like many of my previous mails stated) are meant as building
    blocks to higher-level AIO interfaces such as in glibc or libaio. Then
    user-space can build its state-machine based on syslet-implemented
    glibc/libaio. In that specific role they are a very fast and scalable
    mechanism.

    Ingo
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