Re: Linux futexes

[Jason Thorpe <thorpej%me.com@localhost>]

But glibc might be using the PI operations, which we don’t implement yet.

-- thorpej
Sent from my iPhone.

> On Jul 27, 2019, at 7:51 AM, Robert Swindells <rjs%fdy2.co.uk@localhost> wrote:
> 
> 
> Jason Thorpe <thorpej%me.com@localhost> wrote:
>>> On Jul 27, 2019, at 5:05 AM, Robert Swindells <rjs%fdy2.co.uk@localhost> wrote:
>>> 
>>> I don't think the Linux futex emulation code is correct/good enough.
>> 
>> I have be on/off working on an updated futex implementation written by
>> Taylor, with the intent of making it a native call (in order to improve
>> or own semaphore and mutex implementations).  You are correct in that
>> the current implementation is lacking.
>> 
>> I will try to focus on finishing up the new implementation soon.  But
>> even the stuff written by Taylor is a little lacking compared to what
>> modern Linux uses futexes for, so some additional work is going to be
>> required.
> 
> Linux OpenJDK isn't using any extra futex features, it isn't using a
> bitmask to selectively wake up threads for example, it just seems to
> get into a loop of waking threads up then all of them going back to
> sleep.
> 
> Robert Swindells