Re: [patch 00/11] ANNOUNCE: "Syslets", generic asynchronous system call support

[Ingo Molnar]

* Evgeniy Polyakov <johnpol@xxxxxxxxxxx> 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.)

	Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/