Messages in this thread | | | Date | Tue, 13 Feb 2007 23:18:10 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 00/11] ANNOUNCE: "Syslets", generic asynchronous system call support |
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* Evgeniy Polyakov <johnpol@2ka.mipt.ru> wrote:
> [...] it still has a problem - syscall blocks and the same thread thus > is not allowed to continue execution and fill the pipe - so what if > system issues thousands of requests and there are only tens of working > thread at most. [...]
the same thread is allowed to continue execution even if the system call blocks: take a look at async_schedule(). The blocked system-call is 'put aside' (in a sleeping thread), the kernel switches the user-space context (registers) to a free kernel thread and switches to it - and returns to user-space as if nothing happened - allowing the user-space context to 'fill the pipe' as much as it can. Or did i misunderstand your point?
basically there's SYSLET_ASYNC for 'always async' and SYSLET_SYNC for 'always sync' - but the default syslet behavior is: 'try sync and switch transparently to async on demand'. The testcode i sent very much uses this. (and this mechanism is in essence Zach's fibril-switching thing, but done via kernel threads.)
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