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* Re: [RFC PATCH v2 00/13] Add futex2 syscall
       [not found] <[email protected]>
@ 2021-03-07 11:34 ` Stefan Metzmacher
  2021-03-07 11:56   ` Daurnimator
  2021-03-08 11:11   ` David Laight
  0 siblings, 2 replies; 5+ messages in thread
From: Stefan Metzmacher @ 2021-03-07 11:34 UTC (permalink / raw)
  To: André Almeida, Thomas Gleixner, Ingo Molnar, Peter Zijlstra,
	Darren Hart, linux-kernel, Steven Rostedt,
	Sebastian Andrzej Siewior
  Cc: kernel, krisman, pgriffais, z.figura12, joel, malteskarupke,
	linux-api, fweimer, libc-alpha, linux-kselftest, shuah, acme,
	corbet, io-uring


Hi André,
>  ** The wait on multiple problem
> 
>  The use case lies in the Wine implementation of the Windows NT interface
>  WaitMultipleObjects. This Windows API function allows a thread to sleep
>  waiting on the first of a set of event sources (mutexes, timers, signal,
>  console input, etc) to signal.  

With that in mind would it be good to have some interaction with epoll (and similar calls)?

Instead of having a blocked futex_waitv() waiting on an fd (maybe a generic eventfd() or a new futex2fd())
would be a better interface?

Or instead introduce an IORING_OP_FUTEX2_WAITV? Then the futex_waitv logic wait
in an io-wq kernel thread...

I guess the io_uring way would mean we could have that in mind as future addition, which can be implemented
later...

metze

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [RFC PATCH v2 00/13] Add futex2 syscall
  2021-03-07 11:34 ` [RFC PATCH v2 00/13] Add futex2 syscall Stefan Metzmacher
@ 2021-03-07 11:56   ` Daurnimator
  2021-03-08 11:52     ` Stefan Metzmacher
  2021-03-08 11:11   ` David Laight
  1 sibling, 1 reply; 5+ messages in thread
From: Daurnimator @ 2021-03-07 11:56 UTC (permalink / raw)
  To: Stefan Metzmacher
  Cc: André Almeida, Thomas Gleixner, Ingo Molnar, Peter Zijlstra,
	Darren Hart, linux-kernel, Steven Rostedt,
	Sebastian Andrzej Siewior, kernel, krisman, pgriffais, z.figura12,
	joel, malteskarupke, linux-api, Florian Weimer, GNU C Library,
	linux-kselftest, shuah, Arnaldo Carvalho de Melo, corbet,
	io-uring

On Sun, 7 Mar 2021 at 22:35, Stefan Metzmacher <[email protected]> wrote:
> Instead of having a blocked futex_waitv() waiting on an fd (maybe a generic eventfd() or a new futex2fd())
> would be a better interface?

Like bring back FUTEX_FD? (which was removed back in 2.6.25)

^ permalink raw reply	[flat|nested] 5+ messages in thread

* RE: [RFC PATCH v2 00/13] Add futex2 syscall
  2021-03-07 11:34 ` [RFC PATCH v2 00/13] Add futex2 syscall Stefan Metzmacher
  2021-03-07 11:56   ` Daurnimator
@ 2021-03-08 11:11   ` David Laight
  2021-03-08 11:55     ` Stefan Metzmacher
  1 sibling, 1 reply; 5+ messages in thread
From: David Laight @ 2021-03-08 11:11 UTC (permalink / raw)
  To: 'Stefan Metzmacher', André Almeida, Thomas Gleixner,
	Ingo Molnar, Peter Zijlstra, Darren Hart,
	[email protected], Steven Rostedt,
	Sebastian Andrzej Siewior
  Cc: [email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected], [email protected], io-uring

From: Stefan Metzmacher
> Sent: 07 March 2021 11:35
> 
> Hi André,
> >  ** The wait on multiple problem
> >
> >  The use case lies in the Wine implementation of the Windows NT interface
> >  WaitMultipleObjects. This Windows API function allows a thread to sleep
> >  waiting on the first of a set of event sources (mutexes, timers, signal,
> >  console input, etc) to signal.

They are all events.
You can only wait on either events or sockets (using select).
There is a socket api to signal an event when data arrives (etc).
There is also the insane (these days) restriction of 64 events.

> With that in mind would it be good to have some interaction with epoll (and similar calls)?

Or hook something up so that pollwakeup can kick a futex as well
as waking up poll() and adding an event to epoll().

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [RFC PATCH v2 00/13] Add futex2 syscall
  2021-03-07 11:56   ` Daurnimator
@ 2021-03-08 11:52     ` Stefan Metzmacher
  0 siblings, 0 replies; 5+ messages in thread
From: Stefan Metzmacher @ 2021-03-08 11:52 UTC (permalink / raw)
  To: Daurnimator
  Cc: André Almeida, Thomas Gleixner, Ingo Molnar, Peter Zijlstra,
	Darren Hart, linux-kernel, Steven Rostedt,
	Sebastian Andrzej Siewior, kernel, krisman, pgriffais, z.figura12,
	joel, malteskarupke, linux-api, Florian Weimer, GNU C Library,
	linux-kselftest, shuah, Arnaldo Carvalho de Melo, corbet,
	io-uring


Am 07.03.21 um 12:56 schrieb Daurnimator:
> On Sun, 7 Mar 2021 at 22:35, Stefan Metzmacher <[email protected]> wrote:
>> Instead of having a blocked futex_waitv() waiting on an fd (maybe a generic eventfd() or a new futex2fd())
>> would be a better interface?
> 
> Like bring back FUTEX_FD? (which was removed back in 2.6.25)

Ah, ok, yes something like that.

But as that was removed because of races, but might not be a good idea to bring it back.

metze

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [RFC PATCH v2 00/13] Add futex2 syscall
  2021-03-08 11:11   ` David Laight
@ 2021-03-08 11:55     ` Stefan Metzmacher
  0 siblings, 0 replies; 5+ messages in thread
From: Stefan Metzmacher @ 2021-03-08 11:55 UTC (permalink / raw)
  To: David Laight, André Almeida, Thomas Gleixner, Ingo Molnar,
	Peter Zijlstra, Darren Hart, [email protected],
	Steven Rostedt, Sebastian Andrzej Siewior
  Cc: [email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected],
	[email protected], [email protected], [email protected], io-uring

Am 08.03.21 um 12:11 schrieb David Laight:
> From: Stefan Metzmacher
>> Sent: 07 March 2021 11:35
>>
>> Hi André,
>>>  ** The wait on multiple problem
>>>
>>>  The use case lies in the Wine implementation of the Windows NT interface
>>>  WaitMultipleObjects. This Windows API function allows a thread to sleep
>>>  waiting on the first of a set of event sources (mutexes, timers, signal,
>>>  console input, etc) to signal.
> 
> They are all events.
> You can only wait on either events or sockets (using select).
> There is a socket api to signal an event when data arrives (etc).
> There is also the insane (these days) restriction of 64 events.

Ok.

>> With that in mind would it be good to have some interaction with epoll (and similar calls)?
> 
> Or hook something up so that pollwakeup can kick a futex as well
> as waking up poll() and adding an event to epoll().

I guess as FUTEX_FD was already there and was removed we can stop this discussion.

If there will every be the need to an async call, I guess a io_uring based one would
be the best...

metze


^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2021-03-08 11:56 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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     [not found] <[email protected]>
2021-03-07 11:34 ` [RFC PATCH v2 00/13] Add futex2 syscall Stefan Metzmacher
2021-03-07 11:56   ` Daurnimator
2021-03-08 11:52     ` Stefan Metzmacher
2021-03-08 11:11   ` David Laight
2021-03-08 11:55     ` Stefan Metzmacher

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